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38152b626b
[ Upstream commit 88b1bb1f3b ]
Currently the link_state is uninitialized and the default value is 0(U0)
before the first time we start the udc, and after we start the udc then
stop the udc, the link_state will be undefined.
We may have the following warnings if we start the udc again with
an undefined link_state:
WARNING: CPU: 0 PID: 327 at drivers/usb/dwc3/gadget.c:294 dwc3_send_gadget_ep_cmd+0x304/0x308
dwc3 100e0000.hidwc3_0: wakeup failed --> -22
[...]
Call Trace:
[<c010f270>] (unwind_backtrace) from [<c010b3d8>] (show_stack+0x10/0x14)
[<c010b3d8>] (show_stack) from [<c034a4dc>] (dump_stack+0x84/0x98)
[<c034a4dc>] (dump_stack) from [<c0118000>] (__warn+0xe8/0x100)
[<c0118000>] (__warn) from [<c0118050>](warn_slowpath_fmt+0x38/0x48)
[<c0118050>] (warn_slowpath_fmt) from [<c0442ec0>](dwc3_send_gadget_ep_cmd+0x304/0x308)
[<c0442ec0>] (dwc3_send_gadget_ep_cmd) from [<c0445e68>](dwc3_ep0_start_trans+0x48/0xf4)
[<c0445e68>] (dwc3_ep0_start_trans) from [<c0446750>](dwc3_ep0_out_start+0x64/0x80)
[<c0446750>] (dwc3_ep0_out_start) from [<c04451c0>](__dwc3_gadget_start+0x1e0/0x278)
[<c04451c0>] (__dwc3_gadget_start) from [<c04452e0>](dwc3_gadget_start+0x88/0x10c)
[<c04452e0>] (dwc3_gadget_start) from [<c045ee54>](udc_bind_to_driver+0x88/0xbc)
[<c045ee54>] (udc_bind_to_driver) from [<c045f29c>](usb_gadget_probe_driver+0xf8/0x140)
[<c045f29c>] (usb_gadget_probe_driver) from [<bf005424>](gadget_dev_desc_UDC_store+0xac/0xc4 [libcomposite])
[<bf005424>] (gadget_dev_desc_UDC_store [libcomposite]) from[<c023d8e0>] (configfs_write_file+0xd4/0x160)
[<c023d8e0>] (configfs_write_file) from [<c01d51e8>] (__vfs_write+0x1c/0x114)
[<c01d51e8>] (__vfs_write) from [<c01d5ff4>] (vfs_write+0xa4/0x168)
[<c01d5ff4>] (vfs_write) from [<c01d6d40>] (SyS_write+0x3c/0x90)
[<c01d6d40>] (SyS_write) from [<c0107400>] (ret_fast_syscall+0x0/0x3c)
Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.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.