linux/drivers/misc
Wang Xin 9a9e295e7c eeprom: at24: fix unexpected timeout under high load
Within at24_loop_until_timeout the timestamp used for timeout checking
is recorded after the I2C transfer and sleep_range(). Under high CPU
load either the execution time for I2C transfer or sleep_range() could
actually be larger than the timeout value. Worst case the I2C transfer
is only tried once because the loop will exit due to the timeout
although the EEPROM is now ready.

To fix this issue the timestamp is recorded at the beginning of each
iteration. That is, before I2C transfer and sleep. Then the timeout
is actually checked against the timestamp of the previous iteration.
This makes sure that even if the timeout is reached, there is still one
more chance to try the I2C transfer in case the EEPROM is ready.

Example:

If you have a system which combines high CPU load with repeated EEPROM
writes you will run into the following scenario.

 - System makes a successful regmap_bulk_write() to EEPROM.
 - System wants to perform another write to EEPROM but EEPROM is still
   busy with the last write.
 - Because of high CPU load the usleep_range() will sleep more than
   25 ms (at24_write_timeout).
 - Within the over-long sleeping the EEPROM finished the previous write
   operation and is ready again.
 - at24_loop_until_timeout() will detect timeout and won't try to write.

Signed-off-by: Wang Xin <xin.wang7@cn.bosch.com>
Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2018-10-02 16:58:21 +02:00
..
altera-stapl treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
c2port
cardreader misc: rtsx: make several functions static 2018-07-03 13:01:48 +02:00
cb710 cb710: Convert to new IDA API 2018-08-21 23:54:18 -04:00
cxl Merge branch 'akpm' (patches from Andrew) 2018-08-17 16:49:31 -07:00
echo misc: Remove Blackfin DSP echo support 2018-03-26 15:56:37 +02:00
eeprom eeprom: at24: fix unexpected timeout under high load 2018-10-02 16:58:21 +02:00
genwqe genwqe: card_base: Use true and false for boolean values 2018-08-05 16:29:11 +02:00
ibmasm ibmasm: don't write out of bounds in read handler 2018-07-07 09:59:35 +02:00
lis3lv02d vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
lkdtm lkdtm: Add missing SPDX-License-Identifier line 2018-03-06 19:18:55 -08:00
mei mei: bus: need to unlink client before freeing 2018-09-12 09:14:24 +02:00
mic mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
ocxl Merge branch 'akpm' (patches from Andrew) 2018-08-17 16:49:31 -07:00
sgi-gru mm, oom: distinguish blockable mode for mmu notifiers 2018-08-22 10:52:44 -07:00
sgi-xp sgi-xp: xpc_partition: mark expected switch fall-throughs 2018-07-07 17:38:57 +02:00
ti-st misc: ti-st: Fix memory leak in the error path of probe() 2018-08-02 10:35:04 +02:00
vmw_vmci vmci: type promotion bug in qp_host_get_user_memory() 2018-07-07 17:32:40 +02:00
ad525x_dpot-i2c.c
ad525x_dpot-spi.c
ad525x_dpot.c
ad525x_dpot.h
apds990x.c
apds9802als.c
aspeed-lpc-ctrl.c misc: aspeed-lpc-ctrl: Enable FWH and A2H bridge cycles 2018-03-15 18:20:51 +01:00
aspeed-lpc-snoop.c drivers/misc: Aspeed LPC snoop output using misc chardev 2018-07-16 13:30:47 +02:00
atmel_tclib.c
atmel-ssc.c
bh1770glc.c
cs5535-mfgpt.c
ds1682.c
dummy-irq.c
enclosure.c
fsa9480.c
hmc6352.c misc: hmc6352: fix potential Spectre v1 2018-09-12 09:31:00 +02:00
hpilo.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hpilo.h
ibmvmc.c misc: ibmvsm: Fix wrong assignment of return code 2018-09-12 09:31:00 +02:00
ibmvmc.h misc: IBM Virtual Management Channel Driver (VMC) 2018-05-14 16:35:42 +02:00
ics932s401.c
ioc4.c
isl29003.c
isl29020.c
Kconfig misc: IBM Virtual Management Channel Driver (VMC) 2018-05-14 16:35:42 +02:00
kgdbts.c
lattice-ecp3-config.c
Makefile misc: IBM Virtual Management Channel Driver (VMC) 2018-05-14 16:35:42 +02:00
pch_phub.c
pci_endpoint_test.c pci_endpoint_test: Add 2 ioctl commands 2018-07-19 11:46:57 +01:00
phantom.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pti.c
qcom-coincell.c
spear13xx_pcie_gadget.c
sram-exec.c
sram.c misc: sram: enable clock before registering regions 2018-07-06 16:48:15 +02:00
sram.h
tifm_7xx1.c misc: tifm: Remove VLA 2018-04-23 13:31:27 +02:00
tifm_core.c
tsl2550.c tsl2550: fix lux1_input error in low light 2018-07-07 17:44:52 +02:00
vexpress-syscfg.c misc: vexpress/syscfg: Use devm_ioremap_resource() to map memory 2018-07-16 13:32:08 +02:00
vmw_balloon.c Merge 4.18-rc5 into char-misc-next 2018-07-16 09:04:54 +02:00