Commit Graph

334 Commits

Author SHA1 Message Date
Chandrakanth Patil
299ee42615 scsi: megaraid_sas: Introduce various Aero performance modes
For Aero adapters, driver provides three different performance modes
controlled through module parameter named 'perf_mode'. Below are those
performance modes:

 0: Balanced - Additional high IOPS reply queues will be enabled along with
    low latency queues. Interrupt coalescing will be enabled only for these
    high IOPS reply queues.

 1: IOPS - No additional high IOPS queues are enabled. Interrupt coalescing
    will be enabled on all reply queues.

 2: Latency - No additional high IOPS queues are enabled. Interrupt
    coalescing will be disabled on all reply queues. This is a legacy
    behavior similar to Ventura & Invader Series.

Default performance mode settings:

 - Performance mode set to 'Balanced', if Aero controller is working in
   16GT/s PCIe speed.

 - Performance mode will be set to 'Latency' mode for all other cases.

Through module parameter 'perf_mode', user can override default performance
mode to desired one.

Captured some performance numbers with these performance modes.  4k Random
Read IO performance numbers on 24 SAS SSD drives for above three
performance modes. Performance data is from Intel Skylake and HGST SS300
(drive model SDLL1DLR400GCCA1).

IOPS:
 -----------------------------------------------------------------------
  |perf_mode    | qd = 1 | qd = 64 |   note                             |
  |-------------|--------|---------|-------------------------------------
  |balanced     |  259K  |  3061k  | Provides max performance numbers   |
  |             |        |         | both on lower QD workload &        |
  |             |        |         | also on higher QD workload         |
  |-------------|--------|---------|-------------------------------------
  |iops         |  220K  |  3100k  | Provides max performance numbers   |
  |             |        |         | only on higher QD workload.        |
  |-------------|--------|---------|-------------------------------------
  |latency      |  246k  |  2226k  | Provides good performance numbers  |
  |             |        |         | only on lower QD worklaod.         |
  -----------------------------------------------------------------------

Average Latency:
  -----------------------------------------------------
  |perf_mode    |  qd = 1      |    qd = 64           |
  |-------------|--------------|----------------------|
  |balanced     |  92.05 usec  |    501.12 usec       |
  |-------------|--------------|----------------------|
  |iops         |  108.40 usec |    498.10 usec       |
  |-------------|--------------|----------------------|
  |latency      |  97.10 usec  |    689.26 usec       |
  -----------------------------------------------------

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:08:50 -04:00
Chandrakanth Patil
f0b9e7bdc3 scsi: megaraid_sas: Set affinity for high IOPS reply queues
High iops queues are mapped to non-managed IRQs. Set affinity of
non-managed irqs to local numa node.  Low latency queues are mapped to
managed IRQs.

Driver reserves some reply queues for high IOPS queues (through
pci_alloc_irq_vectors_affinity and .pre_vectors interface). The rest of
queues are for low latency.

Based on IO workload, driver will decide which group of reply queues
(either high IOPS queues or low latency queues) to be used.
High IOPS queues will be mapped to local numa node of controller and
low latency queues will be mapped to CPUs across numa nodes. In general,
high IOPS and low latency queues should fit into 128 reply queues
which is the max number of reply queues supported by Aero adapters.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:36 -04:00
Chandrakanth Patil
132147d7f6 scsi: megaraid_sas: Add support for High IOPS queues
Aero controllers support balanced performance mode through the ability to
configure queues with different properties.

Reply queues with interrupt coalescing enabled are called "high iops reply
queues" and reply queues with interrupt coalescing disabled are called "low
latency reply queues".

The driver configures a combination of high iops and low latency reply
queues if:

 - HBA is an AERO controller;

 - MSI-X vectors supported by the HBA is 128;

 - Total CPU count in the system more than high iops queue count;

 - Driver is loaded with default max_msix_vectors module parameter; and

 - System booted in non-kdump mode.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
5813685616 scsi: megaraid_sas: Add support for MPI toolbox commands
Added driver support to allow passthrough MPI toolbox type MFI commands to
firmware based on firmware capability.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
7fc557005c scsi: megaraid_sas: Offload Aero RAID5/6 division calculations to driver
For RAID5/RAID6 volumes configured behind Aero, driver will be doing 64bit
division operations on behalf of firmware as controller's ARM CPU is very
slow in this division. Later, driver calculates Q-ARM, P-ARM and Log-ARM and
passes those values to firmware by writing these values to RAID_CONTEXT.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
49f2bf1071 scsi: megaraid_sas: RAID1 PCI bandwidth limit algorithm is applicable for only Ventura
RAID1 PCI bandwidth limit algorithm is not applicable to Aero as it's PCIe
Gen4 adapter.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
a4413a5859 scsi: megaraid_sas: megaraid_sas: Add check for count returned by HOST_DEVICE_LIST DCMD
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
59db5a931b scsi: megaraid_sas: Handle sequence JBOD map failure at driver level
Issue: This issue is applicable to scenario when JBOD sequence map is
unavailable (memory allocation for JBOD sequence map failed) to driver but
feature is supported by firmware.  If the driver sends a JBOD IO by not
adding 255 (MAX_PHYSICAL_DEVICES - 1) to device ID when underlying firmware
supports JBOD sequence map, it will lead to the IO failure.

Fix: For JBOD IOs, driver will not use the RAID map to fetch the devhandle
if JBOD sequence map is unavailable. Driver will set Devhandle to 0xffff
and Target ID to 'device ID + 255 (MAX_PHYSICAL_DEVICES - 1)'.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
7fa3174b3e scsi: megaraid_sas: Release Mutex lock before OCR in case of DCMD timeout
Issue: There is possibility of few DCMDs timing out with 'reset_mutex' lock
held. As part of DCMD timeout handling, driver calls function
megasas_reset_fusion which also tries to acquire same lock 'reset_mutex'
and end up with deadlock.

Fix: Upon timeout of DCMDs (which are fired with 'reset_mutex' lock held),
driver will release 'reset_mutex' before calling OCR function and will
acquire lock again after OCR function returns.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:35 -04:00
Chandrakanth Patil
dd80769923 scsi: megaraid_sas: Add support for Non-secure Aero PCI IDs
This patch will add support for non-secure Aero adapter PCI IDs.  Driver
will throw an error message when a non-secure type controller is
detected. Purpose of this interface is to avoid interacting with any
firmware which is not secured/signed by Broadcom. Any tampering on Firmware
component will be detected by hardware and it will be communicated to the
driver to avoid any further interaction with that component.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-27 00:07:34 -04:00
Tomas Henzl
d635468349 scsi: megaraid_sas: use DEVICE_ATTR_{RO, RW}
Use existing macros.  No functional change.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:25 -04:00
Tomas Henzl
ea14e46240 scsi: megaraid_sas: use octal permissions instead of constants
Checkpatch emits a warning when using symbolic permissions. Use octal
permissions instead.  No functional change.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:25 -04:00
Tomas Henzl
deff370633 scsi: megaraid_sas: make max_sectors visible in sys
Support is easier with all driver parameters visible in sysfs.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:25 -04:00
YueHaibing
cdf79db476 scsi: megaraid_sas: remove set but not used variables 'buff_addr' and 'ci_h'
Fixes gcc '-Wunused-but-set-variable' warnings:

drivers/scsi/megaraid/megaraid_sas_base.c: In function megasas_fw_crash_buffer_show:
drivers/scsi/megaraid/megaraid_sas_base.c:3138:16: warning: variable buff_addr set but not used [-Wunused-but-set-variable]
drivers/scsi/megaraid/megaraid_sas_base.c: In function megasas_get_pd_list:
drivers/scsi/megaraid/megaraid_sas_base.c:4426:13: warning: variable ci_h set but not used [-Wunused-but-set-variable]

'buff_addr' is never used since inroduction in commit fc62b3fc90
("megaraid_sas : Firmware crash dump feature support")

'ci_h' is not used since commit 9b3d028f34 ("scsi: megaraid_sas:
Pre-allocate frequently used DMA buffers")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:25 -04:00
YueHaibing
ed17190941 scsi: megaraid_sas: remove set but not used variable 'sge_sz'
Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/megaraid/megaraid_sas_base.c: In function megasas_create_frame_pool:
drivers/scsi/megaraid/megaraid_sas_base.c:4124:6: warning: variable sge_sz set but not used [-Wunused-but-set-variable]

It's not used any more since commit 200aed582d ("megaraid_sas: endianness
related bug fixes and code optimization")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:25 -04:00
YueHaibing
de19212c28 scsi: megaraid_sas: remove set but not used variables 'host' and 'wait_time'
Fixes gcc '-Wunused-but-set-variable' warnings:

drivers/scsi/megaraid/megaraid_sas_base.c: In function megasas_suspend:
drivers/scsi/megaraid/megaraid_sas_base.c:7269:20: warning: variable host set but not used [-Wunused-but-set-variable]
drivers/scsi/megaraid/megaraid_sas_base.c: In function megasas_aen_polling:
drivers/scsi/megaraid/megaraid_sas_base.c:8397:15: warning: variable wait_time set but not used [-Wunused-but-set-variable]

'host' never used since introduction in commit 31ea708897 ("[SCSI]
megaraid_sas: add hibernation support")

'wait_time' never used since commit 11c71cb4ab ("megaraid_sas: Do
not allow PCI access during OCR")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:23 -04:00
YueHaibing
dea98ba45a scsi: megaraid_sas: remove set but not used variable 'cur_state'
Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/megaraid/megaraid_sas_base.c: In function megasas_transition_to_ready:
drivers/scsi/megaraid/megaraid_sas_base.c:3900:6: warning: variable cur_state set but not used [-Wunused-but-set-variable]

Never used since commit 7218df69e3 ("[SCSI] megaraid_sas: use the
firmware boot timeout when waiting for commands")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:23 -04:00
Shivasharan S
ba53572bf0 scsi: megaraid_sas: Export RAID map through debugfs
Create a debugfs interface for megaraid_sas driver.  Provide interface to
dump driver RAID map in debugfs.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:20 -04:00
Shivasharan S
ce88418dce scsi: megaraid_sas: Fix MSI-X vector print
Print FW supported MSI-X vector count only if FW supports
MSI-X.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:20 -04:00
Shivasharan S
0a11c0b02a scsi: megaraid_sas: Add debug prints for device list
Add debug prints related to device list being returned by firmware.  The a
debug flag to activate these prints.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:20 -04:00
Shivasharan S
f7331f1800 scsi: megaraid_sas: Add prints in suspend and resume path
Add prints in resume/suspend path to help in debugging hibernation
issues. The print gives an indication when the driver entry points are
called.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:20 -04:00
Shivasharan S
b6661342f2 scsi: megaraid_sas: Print FW fault information
When driver detects a firmware fault during load, dump additional
information on fault code and subcode that will help in debugging.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:20 -04:00
Shivasharan S
a6024a9e91 scsi: megaraid_sas: Export RAID map id through sysfs
Add a sysfs interface to get the raid map index that is being used by
driver.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:20 -04:00
Shivasharan S
9a5987101c scsi: megaraid_sas: Print BAR information from driver
Add prints for BAR address information during driver load.  This helps in
debugging issues with BAR address changing during OS boot.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
3d1d9eb7f2 scsi: megaraid_sas: Dump system registers for debugging
When controller fails to transition to READY state during driver probe,
dump the system interface register set.  This will give snapshot of the
firmware status for debugging driver load issues.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
cfb9a30e5d scsi: megaraid_sas: Dump system interface regs from sysfs
Add a sysfs interface to dump the controller's system interface registers.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
4fe55035f3 scsi: megaraid_sas: Add formatting option for megasas_dump
Add option to format the buffer that is being dumped.  Currently, the IO
frame and chain frame dumped in the syslog is getting split across multiple
lines based on the formatting.  Fix this by using KERN_CONT in printk.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
2ce4350879 scsi: megaraid_sas: Enhance internal DCMD timeout prints
Add prints to identify the internal DCMD opcode that has timed out.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
96c9603cf1 scsi: megaraid_sas: Enhance prints in OCR and TM path
This patch enhances the existing debug prints in reset and task management
path.

These debug prints in adapter reset path helps with debugging issues
related to IO timeouts that are seen frequently in the field.  Add
additional debug prints to dump the pending command frames before
initiating an adapter reset.  Also, print FastPath IOs that are
outstanding.

Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
1d15d9098a scsi: megaraid_sas: Load balance completions across all MSI-X
Driver will use "reply descriptor post queues" in round robin fashion when
the combined MSI-X mode is not enabled. With this IO completions are
distributed and load balanced across all the available reply descriptor
post queues equally.

This is enabled only if combined MSI-X mode is not enabled in firmware.
This improves performance and also fixes soft lockups.

When load balancing is enabled, IRQ affinity from driver needs to be
disabled.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
62a04f81e6 scsi: megaraid_sas: IRQ poll to avoid CPU hard lockups
Issue Description:

We have seen cpu lock up issues from field if system has a large (more than
96) logical cpu count.  SAS3.0 controller (Invader series) supports max 96
MSI-X vector and SAS3.5 product (Ventura) supports max 128 MSI-X vectors.

This may be a generic issue (if PCI device support completion on multiple
reply queues).

Let me explain it w.r.t megaraid_sas supported h/w just to simplify the
problem and possible changes to handle such issues.  MegaRAID controller
supports multiple reply queues in completion path.  Driver creates MSI-X
vectors for controller as "minimum of (FW supported Reply queues, Logical
CPUs)".  If submitter is not interrupted via completion on same CPU, there
is a loop in the IO path. This behavior can cause hard/soft CPU lockups, IO
timeout, system sluggish etc.

Example - one CPU (e.g. CPU A) is busy submitting the IOs and another CPU
(e.g. CPU B) is busy with processing the corresponding IO's reply
descriptors from reply descriptor queue upon receiving the interrupts from
HBA.  If CPU A is continuously pumping the IOs then always CPU B (which is
executing the ISR) will see the valid reply descriptors in the reply
descriptor queue and it will be continuously processing those reply
descriptor in a loop without quitting the ISR handler.

megaraid_sas driver will exit ISR handler if it finds unused reply
descriptor in the reply descriptor queue.  Since CPU A will be continuously
sending the IOs, CPU B may always see a valid reply descriptor (posted by
HBA Firmware after processing the IO) in the reply descriptor queue. In
worst case, driver will not quit from this loop in the ISR handler.
Eventually, CPU lockup will be detected by watchdog.

Above mentioned behavior is not common if "rq_affinity" set to 2 or
affinity_hint is honored by irqbalancer as "exact".  If rq_affinity is set
to 2, submitter will be always interrupted via completion on same CPU.  If
irqbalancer is using "exact" policy, interrupt will be delivered to
submitter CPU.

Problem statement:

If CPU count to MSI-X vectors (reply descriptor Queues) count ratio is not
1:1, we still have exposure of issue explained above and for that we don't
have any solution.

Exposure of soft/hard lockup is seen if CPU count is more than MSI-X
supported by device.

If CPUs count to MSI-X vectors count ratio is not 1:1, (Other way, if
CPU counts to MSI-X vector count ratio is something like X:1, where X > 1)
then 'exact' irqbalance policy OR rq_affinity = 2 won't help to avoid CPU
hard/soft lockups. There won't be any one to one mapping between
CPU to MSI-X vector instead one MSI-X interrupt (or reply descriptor queue)
is shared with group/set of CPUs and there is a possibility of having a
loop in the IO path within that CPU group and may observe lockups.

For example: Consider a system having two NUMA nodes and each node having
four logical CPUs and also consider that number of MSI-X vectors enabled on
the HBA is two, then CPUs count to MSI-X vector count ratio as 4:1.
e.g.
MSI-X vector 0 is affinity to CPU 0, CPU 1, CPU 2 & CPU 3 of NUMA node 0 and
MSI-X vector 1 is affinity to CPU 4, CPU 5, CPU 6 & CPU 7 of NUMA node 1.

numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3                 --> MSI-X 0
node 0 size: 65536 MB
node 0 free: 63176 MB
node 1 cpus: 4 5 6 7                 --> MSI-X 1
node 1 size: 65536 MB
node 1 free: 63176 MB

Assume that user started an application which uses all the CPUs of NUMA
node 0 for issuing the IOs.  Only one CPU from affinity list (it can be any
cpu since this behavior depends upon irqbalance) CPU0 will receive the
interrupts from MSI-X 0 for all the IOs. Eventually, CPU 0 IO submission
percentage will be decreasing and ISR processing percentage will be
increasing as it is more busy with processing the interrupts.  Gradually IO
submission percentage on CPU 0 will be zero and it's ISR processing
percentage will be 100% as IO loop has already formed within the
NUMA node 0, i.e. CPU 1, CPU 2 & CPU 3 will be continuously busy with
submitting the heavy IOs and only CPU 0 is busy in the ISR path as it
always find the valid reply descriptor in the reply descriptor queue.
Eventually, we will observe the hard lockup here.

Chances of occurring of hard/soft lockups are directly proportional to
value of X. If value of X is high, then chances of observing CPU lockups is
high.

Solution:

Use IRQ poll interface defined in "irq_poll.c".

megaraid_sas driver will execute ISR routine in softirq context and it will
always quit the loop based on budget provided in IRQ poll interface.
Driver will switch to IRQ poll only when more than a threshold number of
reply descriptors are handled in one ISR. Currently threshold is set as
1/4th of HBA queue depth.

In these scenarios (i.e. where CPUs count to MSI-X vectors count ratio is
X:1 (where X >  1)), IRQ poll interface will avoid CPU hard lockups due to
voluntary exit from the reply queue processing based on budget.
Note - Only one MSI-X vector is busy doing processing.

Select CONFIG_IRQ_POLL from driver Kconfig for driver compilation.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
78409d4b47 scsi: megaraid_sas: Block PCI config space access from userspace during OCR
While an online controller reset(OCR) is in progress, there is short
duration where all access to controller's PCI config space from the host
needs to be blocked.  This is due to a hardware limitation of MegaRAID
controllers.

With this patch, driver will block all access to controller's config space
from userland applications by calling pci_cfg_access_lock() while OCR is in
progress and unlocking after controller comes back to ready state.

Added helper function which locks the config space before initiating OCR
and wait for controller to become READY.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
f10fb8523a scsi: megaraid_sas: fw_reset_no_pci_access required for MFI adapters only
fw_reset_no_pci_access is only applicable for MFI controllers and is not
used for Fusion controllers.

For all Fusion controllers, driver can check reset adapter bit in
status register before performing a chip reset without
setting "fw_reset_no_pci_access".

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Shivasharan S
4a0bcf362d scsi: megaraid_sas: Remove unused variable target_index
No functional change. Remove set but unused variable in
megasas_set_static_target_properties.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-06-18 19:46:19 -04:00
Linus Torvalds
d1cd7c85f9 SCSI misc on 20190507
This is mostly update of the usual drivers: qla2xxx, qedf, smartpqi,
 hpsa, lpfc, ufs, mpt3sas, ibmvfc and hisi_sas.  Plus number of minor
 changes, spelling fixes and other trivia.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
 -----BEGIN PGP SIGNATURE-----
 
 iJwEABMIAEQWIQTnYEDbdso9F2cI+arnQslM7pishQUCXNIK0yYcamFtZXMuYm90
 dG9tbGV5QGhhbnNlbnBhcnRuZXJzaGlwLmNvbQAKCRDnQslM7pishbeFAP4wsOm6
 BNqDvLbF7gHAH+oSVAeENd9tepXG2xKbUHmLRgEA1wPaUxon8L8v/SSsqwewqMXP
 y6CnU6aO2iaViTNBsPs=
 =RX74
 -----END PGP SIGNATURE-----

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI updates from James Bottomley:
 "This is mostly update of the usual drivers: qla2xxx, qedf, smartpqi,
  hpsa, lpfc, ufs, mpt3sas, ibmvfc and hisi_sas. Plus number of minor
  changes, spelling fixes and other trivia"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (298 commits)
  scsi: qla2xxx: Avoid that lockdep complains about unsafe locking in tcm_qla2xxx_close_session()
  scsi: qla2xxx: Avoid that qlt_send_resp_ctio() corrupts memory
  scsi: qla2xxx: Fix hardirq-unsafe locking
  scsi: qla2xxx: Complain loudly about reference count underflow
  scsi: qla2xxx: Use __le64 instead of uint32_t[2] for sending DMA addresses to firmware
  scsi: qla2xxx: Introduce the dsd32 and dsd64 data structures
  scsi: qla2xxx: Check the size of firmware data structures at compile time
  scsi: qla2xxx: Pass little-endian values to the firmware
  scsi: qla2xxx: Fix race conditions in the code for aborting SCSI commands
  scsi: qla2xxx: Use an on-stack completion in qla24xx_control_vp()
  scsi: qla2xxx: Make qla24xx_async_abort_cmd() static
  scsi: qla2xxx: Remove unnecessary locking from the target code
  scsi: qla2xxx: Remove qla_tgt_cmd.released
  scsi: qla2xxx: Complain if a command is released that is owned by the firmware
  scsi: qla2xxx: target: Fix offline port handling and host reset handling
  scsi: qla2xxx: Fix abort handling in tcm_qla2xxx_write_pending()
  scsi: qla2xxx: Fix error handling in qlt_alloc_qfull_cmd()
  scsi: qla2xxx: Simplify qlt_send_term_imm_notif()
  scsi: qla2xxx: Fix use-after-free issues in qla2xxx_qpair_sp_free_dma()
  scsi: qla2xxx: Fix a qla24xx_enable_msix() error path
  ...
2019-05-08 10:12:46 -07:00
Colin Ian King
efc372c1bf scsi: megaraid_sas: fix spelling mistake "oustanding" -> "outstanding"
There are a couple of spelling mistakes in some kernel info and notice
messages. Fix these.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-04-18 20:34:46 -04:00
YueHaibing
7c3f8ca8e4 scsi: megaraid_sas: Make megasas_host_device_list_query() static
Fix sparse warning:

drivers/scsi/megaraid/megaraid_sas_base.c:4652:1: warning:
 symbol 'megasas_host_device_list_query' was not declared. Should it be static?

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-04-15 22:20:16 -04:00
Will Deacon
fb24ea52f7 drivers: Remove explicit invocations of mmiowb()
mmiowb() is now implied by spin_unlock() on architectures that require
it, so there is no reason to call it from driver code. This patch was
generated using coccinelle:

	@mmiowb@
	@@
	- mmiowb();

and invoked as:

$ for d in drivers include/linux/qed sound; do \
spatch --include-headers --sp-file mmiowb.cocci --dir $d --in-place; done

NOTE: mmiowb() has only ever guaranteed ordering in conjunction with
spin_unlock(). However, pairing each mmiowb() removal in this patch with
the corresponding call to spin_unlock() is not at all trivial, so there
is a small chance that this change may regress any drivers incorrectly
relying on mmiowb() to order MMIO writes between CPUs using lock-free
synchronisation. If you've ended up bisecting to this commit, you can
reintroduce the mmiowb() calls using wmb() instead, which should restore
the old behaviour on all architectures other than some esoteric ia64
systems.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-08 12:01:02 +01:00
Linus Torvalds
477558d7e8 SCSI misc on 20190315
This is the final round of mostly small fixes and performance
 improvements to our initial submit.  The main regression fix is the
 ia64 simscsi build failure which was missed in the serial number
 elimination conversion.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
 -----BEGIN PGP SIGNATURE-----
 
 iJwEABMIAEQWIQTnYEDbdso9F2cI+arnQslM7pishQUCXIxBayYcamFtZXMuYm90
 dG9tbGV5QGhhbnNlbnBhcnRuZXJzaGlwLmNvbQAKCRDnQslM7pisherpAP4rxLpX
 bcUnQnEsvoxys/JyoK08Qfv1JebZo1B2MAZ62wD/VZ7LpOuzVLhsM2KhLFGRrs1/
 7D2K4tgtO2dQsFix7H0=
 =pcHl
 -----END PGP SIGNATURE-----

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull more SCSI updates from James Bottomley:
 "This is the final round of mostly small fixes and performance
  improvements to our initial submit.

  The main regression fix is the ia64 simscsi build failure which was
  missed in the serial number elimination conversion"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (24 commits)
  scsi: ia64: simscsi: use request tag instead of serial_number
  scsi: aacraid: Fix performance issue on logical drives
  scsi: lpfc: Fix error codes in lpfc_sli4_pci_mem_setup()
  scsi: libiscsi: Hold back_lock when calling iscsi_complete_task
  scsi: hisi_sas: Change SERDES_CFG init value to increase reliability of HiLink
  scsi: hisi_sas: Send HARD RESET to clear the previous affiliation of STP target port
  scsi: hisi_sas: Set PHY linkrate when disconnected
  scsi: hisi_sas: print PHY RX errors count for later revision of v3 hw
  scsi: hisi_sas: Fix a timeout race of driver internal and SMP IO
  scsi: hisi_sas: Change return variable type in phy_up_v3_hw()
  scsi: qla2xxx: check for kstrtol() failure
  scsi: lpfc: fix 32-bit format string warning
  scsi: lpfc: fix unused variable warning
  scsi: target: tcmu: Switch to bitmap_zalloc()
  scsi: libiscsi: fall back to sendmsg for slab pages
  scsi: qla2xxx: avoid printf format warning
  scsi: lpfc: resolve static checker warning in lpfc_sli4_hba_unset
  scsi: lpfc: Correct __lpfc_sli_issue_iocb_s4 lockdep check
  scsi: ufs: hisi: fix ufs_hba_variant_ops passing
  scsi: qla2xxx: Fix panic in qla_dfs_tgt_counters_show
  ...
2019-03-16 12:51:50 -07:00
Linus Torvalds
92fff53b71 SCSI misc on 20190306
This is mostly update of the usual drivers: arcmsr, qla2xxx, lpfc,
 hisi_sas, target/iscsi and target/core.  Additionally Christoph
 refactored gdth as part of the dma changes.  The major mid-layer
 change this time is the removal of bidi commands and with them the
 whole of the osd/exofs driver and filesystem.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
 -----BEGIN PGP SIGNATURE-----
 
 iJwEABMIAEQWIQTnYEDbdso9F2cI+arnQslM7pishQUCXIC54SYcamFtZXMuYm90
 dG9tbGV5QGhhbnNlbnBhcnRuZXJzaGlwLmNvbQAKCRDnQslM7pishT1GAPwJEV23
 ExPiPsnuVgKj49nLTagZ3rILRQcYNbL+MNYqxQEA0cT8FHzSDBfWY5OKPNE+RQ8z
 f69LpXGmMpuagKGvvd4=
 =Fhy1
 -----END PGP SIGNATURE-----

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI updates from James Bottomley:
 "This is mostly update of the usual drivers: arcmsr, qla2xxx, lpfc,
  hisi_sas, target/iscsi and target/core.

  Additionally Christoph refactored gdth as part of the dma changes. The
  major mid-layer change this time is the removal of bidi commands and
  with them the whole of the osd/exofs driver and filesystem. This is a
  major simplification for block and mq in particular"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (240 commits)
  scsi: cxgb4i: validate tcp sequence number only if chip version <= T5
  scsi: cxgb4i: get pf number from lldi->pf
  scsi: core: replace GFP_ATOMIC with GFP_KERNEL in scsi_scan.c
  scsi: mpt3sas: Add missing breaks in switch statements
  scsi: aacraid: Fix missing break in switch statement
  scsi: kill command serial number
  scsi: csiostor: drop serial_number usage
  scsi: mvumi: use request tag instead of serial_number
  scsi: dpt_i2o: remove serial number usage
  scsi: st: osst: Remove negative constant left-shifts
  scsi: ufs-bsg: Allow reading descriptors
  scsi: ufs: Allow reading descriptor via raw upiu
  scsi: ufs-bsg: Change the calling convention for write descriptor
  scsi: ufs: Remove unused device quirks
  Revert "scsi: ufs: disable vccq if it's not needed by UFS device"
  scsi: megaraid_sas: Remove a bunch of set but not used variables
  scsi: clean obsolete return values of eh_timed_out
  scsi: sd: Optimal I/O size should be a multiple of physical block size
  scsi: MAINTAINERS: SCSI initiator and target tweaks
  scsi: fcoe: make use of fip_mode enum complete
  ...
2019-03-09 16:53:47 -08:00
Steve Sistare
31b6a05f86 scsi: megaraid_sas: reduce module load time
megaraid_sas takes 1+ seconds to load while waiting for firmware:

[2.822603] megaraid_sas 0000:03:00.0: Waiting for FW to come to ready state
[3.871003] megaraid_sas 0000:03:00.0: FW now in Ready state

This is due to the following loop in megasas_transition_to_ready(), which
waits a minimum of 1 second, even though the FW becomes ready in tens of
millisecs:

        /*
         * The cur_state should not last for more than max_wait secs
         */
        for (i = 0; i < max_wait; i++) {
                ...
                msleep(1000);
        ...
        dev_info(&instance->pdev->dev, "FW now in Ready state\n");

This is a regression, caused by a change of the msleep granularity from 1
to 1000 due to concern about waiting too long on systems with coarse
jiffies.

To fix, increase iterations and use msleep(20), which results in:

[2.670627] megaraid_sas 0000:03:00.0: Waiting for FW to come to ready state
[2.739386] megaraid_sas 0000:03:00.0: FW now in Ready state

Fixes: fb2f3e96d80f ("scsi: megaraid_sas: Fix msleep granularity")
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-03-06 19:26:45 -05:00
Jason Yan
bcf3b67d16 scsi: megaraid_sas: return error when create DMA pool failed
when create DMA pool for cmd frames failed, we should return -ENOMEM,
instead of 0.
In some case in:

    megasas_init_adapter_fusion()

    -->megasas_alloc_cmds()
       -->megasas_create_frame_pool
          create DMA pool failed,
        --> megasas_free_cmds() [1]

    -->megasas_alloc_cmds_fusion()
       failed, then goto fail_alloc_cmds.
    -->megasas_free_cmds() [2]

we will call megasas_free_cmds twice, [1] will kfree cmd_list,
[2] will use cmd_list.it will cause a problem:

Unable to handle kernel NULL pointer dereference at virtual address
00000000
pgd = ffffffc000f70000
[00000000] *pgd=0000001fbf893003, *pud=0000001fbf893003,
*pmd=0000001fbf894003, *pte=006000006d000707
Internal error: Oops: 96000005 [#1] SMP
 Modules linked in:
 CPU: 18 PID: 1 Comm: swapper/0 Not tainted
 task: ffffffdfb9290000 ti: ffffffdfb923c000 task.ti: ffffffdfb923c000
 PC is at megasas_free_cmds+0x30/0x70
 LR is at megasas_free_cmds+0x24/0x70
 ...
 Call trace:
 [<ffffffc0005b779c>] megasas_free_cmds+0x30/0x70
 [<ffffffc0005bca74>] megasas_init_adapter_fusion+0x2f4/0x4d8
 [<ffffffc0005b926c>] megasas_init_fw+0x2dc/0x760
 [<ffffffc0005b9ab0>] megasas_probe_one+0x3c0/0xcd8
 [<ffffffc0004a5abc>] local_pci_probe+0x4c/0xb4
 [<ffffffc0004a5c40>] pci_device_probe+0x11c/0x14c
 [<ffffffc00053a5e4>] driver_probe_device+0x1ec/0x430
 [<ffffffc00053a92c>] __driver_attach+0xa8/0xb0
 [<ffffffc000538178>] bus_for_each_dev+0x74/0xc8
  [<ffffffc000539e88>] driver_attach+0x28/0x34
 [<ffffffc000539a18>] bus_add_driver+0x16c/0x248
 [<ffffffc00053b234>] driver_register+0x6c/0x138
 [<ffffffc0004a5350>] __pci_register_driver+0x5c/0x6c
 [<ffffffc000ce3868>] megasas_init+0xc0/0x1a8
 [<ffffffc000082a58>] do_one_initcall+0xe8/0x1ec
 [<ffffffc000ca7be8>] kernel_init_freeable+0x1c8/0x284
 [<ffffffc0008d90b8>] kernel_init+0x1c/0xe4

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-02-19 18:58:38 -05:00
Shivasharan S
f6fe573108 scsi: megaraid_sas: Add support for DEVICE_LIST DCMD in driver
This patch adds support for the new DEVICE_LIST DCMD.

Driver currently sends two separate DCMDs for getting the list of PDs and
LDs that are exposed to host.  The new DCMD provides a single interface to
get a list of both PDs and LDs that are exposed to the host.  Based on the
list of target IDs that are returned by this DCMD, driver will add the
devices (PD/LD) to SML.  Driver will check for FW support for this new DCMD
and based on the support will either send the new DCMD or will fall back to
the earlier method of sending two separate DCMDs for PD and LD list.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-02-04 22:52:20 -05:00
Shivasharan S
44abbaf64b scsi: megaraid_sas: Rework device add code in AEN path
In preparation of adding support for the DEVICE_LIST DCMD, this patch
refactors the code in the AEN event handling path.  Add new function to
update the PD and LD list in driver.  Move the code to scan PD and VD
channels into separate function.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-02-04 22:52:20 -05:00
Shivasharan S
daa0681118 scsi: megaraid_sas: Rework code to get PD and LD list
During FW init, combine the code to get the PD and LD list from FW into a
single function.  This patch is in preparation for adding support for
HOST_DEVICE_LIST DCMD.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-02-04 22:52:20 -05:00
Linus Torvalds
4d5f6e0201 SCSI fixes on 20190118
A set of 17 fixes.  Most of these are minor or trivial.  The one fix
 that may be serious is the isci one: the bug can cause hba parameters
 to be set from uninitialized memory.  I don't think it's exploitable,
 but you never know.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
 -----BEGIN PGP SIGNATURE-----
 
 iJwEABMIAEQWIQTnYEDbdso9F2cI+arnQslM7pishQUCXEKL0SYcamFtZXMuYm90
 dG9tbGV5QGhhbnNlbnBhcnRuZXJzaGlwLmNvbQAKCRDnQslM7pishVZpAQCwuPTk
 fqOt4v4hJ0oUHtEBsQK3VMXSdUvWdb5Lbn3WeQD/RFYTyNxcIF7ADSWw71b+IigT
 ejUrMzI8ig+nZ1jbFZ4=
 =BdS/
 -----END PGP SIGNATURE-----

Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fixes from James Bottomley:
 "A set of 17 fixes. Most of these are minor or trivial.

  The one fix that may be serious is the isci one: the bug can cause hba
  parameters to be set from uninitialized memory. I don't think it's
  exploitable, but you never know"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: cxgb4i: add wait_for_completion()
  scsi: qla1280: set 64bit coherent mask
  scsi: ufs: Fix geometry descriptor size
  scsi: megaraid_sas: Retry reads of outbound_intr_status reg
  scsi: qedi: Add ep_state for login completion on un-reachable targets
  scsi: ufs: Fix system suspend status
  scsi: qla2xxx: Use correct number of vectors for online CPUs
  scsi: hisi_sas: Set protection parameters prior to adding SCSI host
  scsi: tcmu: avoid cmd/qfull timers updated whenever a new cmd comes
  scsi: isci: initialize shost fully before calling scsi_add_host()
  scsi: lpfc: lpfc_sli: Mark expected switch fall-throughs
  scsi: smartpqi_init: fix boolean expression in pqi_device_remove_start
  scsi: core: Synchronize request queue PM status only on successful resume
  scsi: pm80xx: reduce indentation
  scsi: qla4xxx: check return code of qla4xxx_copy_from_fwddb_param
  scsi: megaraid_sas: correct an info message
  scsi: target/iscsi: fix error msg typo when create lio_qr_cache failed
  scsi: sd: Fix cache_type_store()
2019-01-20 09:15:04 +12:00
Tomas Henzl
d1f38d995e scsi: megaraid_sas: correct an info message
This was apparently forgotten in
894169db1 ("scsi: megaraid_sas: Use 63-bit DMA addressing").

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-01-08 21:57:25 -05:00
Luis Chamberlain
750afb08ca cross-tree: phase out dma_zalloc_coherent()
We already need to zero out memory for dma_alloc_coherent(), as such
using dma_zalloc_coherent() is superflous. Phase it out.

This change was generated with the following Coccinelle SmPL patch:

@ replace_dma_zalloc_coherent @
expression dev, size, data, handle, flags;
@@

-dma_zalloc_coherent(dev, size, handle, flags)
+dma_alloc_coherent(dev, size, handle, flags)

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
[hch: re-ran the script on the latest tree]
Signed-off-by: Christoph Hellwig <hch@lst.de>
2019-01-08 07:58:37 -05:00
Shivasharan S
894169db12 scsi: megaraid_sas: Use 63-bit DMA addressing
Although MegaRAID controllers support 64-bit DMA addressing, as per
hardware design, DMA address with all 64-bits set
(0xFFFFFFFF-FFFFFFFF) results in a firmware fault.

Driver will set 63-bit DMA mask to ensure the above address will not be
used.

Cc: stable@vger.kernel.org
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2018-12-19 21:38:54 -05:00
Shivasharan S
272652fcbf scsi: megaraid_sas: add retry logic in megasas_readl
Due to hardware errata in Aero controllers, reads to certain fusion
registers could intermittently return zero.  This behavior is
transient in nature and subsequent reads will return valid value.

For Aero controllers, any calls to readl to read from certain
registers will be retried for maximum three times, if read returns
zero.

Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2018-12-19 21:37:15 -05:00