0c3aae9bd5
The musb delayed irq work was never flushed on suspend, something which
since 4.9 can lead to an external abort if the work is scheduled after
the grandparent's clock has been disabled:
PM: Suspending system (mem)
PM: suspend of devices complete after 125.224 msecs
PM: suspend devices took 0.132 seconds
PM: late suspend of devices complete after 7.423 msecs
PM: noirq suspend of devices complete after 7.083 msecs
suspend debug: Waiting for 5 second(s).
Unhandled fault: external abort on non-linefetch (0x1008) at 0xd0262c60
...
[<c054880c>] (musb_default_readb) from [<c0547b5c>] (musb_irq_work+0x48/0x220)
[<c0547b5c>] (musb_irq_work) from [<c014f8a4>] (process_one_work+0x1f4/0x758)
[<c014f8a4>] (process_one_work) from [<c014fe5c>] (worker_thread+0x54/0x514)
[<c014fe5c>] (worker_thread) from [<c015704c>] (kthread+0x128/0x158)
[<c015704c>] (kthread) from [<c0109330>] (ret_from_fork+0x14/0x24)
Commit 2bff3916fda9 ("usb: musb: Fix PM for hub disconnect") started
scheduling musb_irq_work with a delay of up to a second and with
retries thereby making this easy to trigger, for example, by suspending
shortly after a disconnect.
Note that we set a flag to prevent the irq work from rescheduling itself
during suspend and instead process a disconnect immediately. This takes
care of the case where we are disconnected shortly before suspending.
However, when in host mode, a disconnect while suspended will still
go unnoticed and thus prevent the controller from runtime suspending
upon resume as the session bit is always set. This will need to be
addressed separately.
Fixes: 550a7375fe72 ("USB: Add MUSB and TUSB support")
Fixes: 467d5c980709 ("usb: musb: Implement session bit based runtime PM for musb-core")
Fixes: 2bff3916fda9 ("usb: musb: Fix PM for hub disconnect")
Cc: stable <stable@vger.kernel.org> # 4.9
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("hub_wq").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.