a1fc1920aa
On am335x-evm with musb in host mode and using it as a wakeup source the following happens once the CPU comes out of suspend to ram: |PM: Wakeup source MPU_WAKE |PM: noirq resume of devices complete after 15.453 msecs |PM: early resume of devices complete after 2.222 msecs |PM: resume of devices complete after 507.351 msecs |Restarting tasks ... |------------[ cut here ]------------ |WARNING: CPU: 0 PID: 322 at drivers/usb/core/urb.c:339 usb_submit_urb+0x494/0x4c8() |URB cc0db380 submitted while active |[<c0348e64>] (usb_submit_urb) from [<c0340f94>] (hub_activate+0x2b8/0x49c) |[<c0340f94>] (hub_activate) from [<c03411dc>] (hub_resume+0x14/0x1c) |[<c03411dc>] (hub_resume) from [<c034be10>] (usb_resume_interface.isra.4+0xdc/0x110) |[<c034be10>] (usb_resume_interface.isra.4) from [<c034beb0>] (usb_resume_both+0x6c/0x13c) |[<c034beb0>] (usb_resume_both) from [<c034cca4>] (usb_runtime_resume+0x10/0x14) |[<c034cca4>] (usb_runtime_resume) from [<c02bbd80>] (__rpm_callback+0x2c/0x60) |[<c02bbd80>] (__rpm_callback) from [<c02bbdd4>] (rpm_callback+0x20/0x74) |[<c02bbdd4>] (rpm_callback) from [<c02bcc48>] (rpm_resume+0x380/0x548) |[<c02bcc48>] (rpm_resume) from [<c02bcb00>] (rpm_resume+0x238/0x548) |[<c02bcb00>] (rpm_resume) from [<c02bd08c>] (__pm_runtime_resume+0x64/0x94) |[<c02bd08c>] (__pm_runtime_resume) from [<c034b5a4>] (usb_autopm_get_interface+0x18/0x5c) |[<c034b5a4>] (usb_autopm_get_interface) from [<c03438b8>] (hub_thread+0x10c/0x115c) |[<c03438b8>] (hub_thread) from [<c005a70c>] (kthread+0xbc/0xd8) |---[ end trace 036aa5fe78203142 ]--- |hub 1-0:1.0: activate --> -16 |hub 2-0:1.0: activate --> -16 The reason for this backtrace is the attempt of the USB code to resume the HUB twice and thus enqueue the status URB twice. Alan Stern was a great help by explaining how the USB code supposed to work and what is most likely the problem. The root problem is that after resume the musb runtime-suspend state remains RPM_SUSPENDED. According to git log it RPM was added for the omap2430 platform. If I understand it correct the omap2430 invokes a get on musb once a cable is connected and a put once the cable is gone. In between the device could go auto-idle/off. Not sure what happens when the device goes into suspend but then I guess it was gadget only. On DSPS I see only a get in probe and put in remove function. This would forbid RPM from working but then the devices enterns suspended state anyway :) To get rid of this warning, I set the device state to RPM_ACTIVE which the expected state. Cc: Alan Stern <stern@rowland.harvard.edu> Cc: <stable@vger.kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Felipe Balbi <balbi@ti.com>
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.