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When a USB2 port initiate a remote wakeup, software shall ensure that resume is signaled for at least 20ms, and then write '0' to the PLS field. According to this, xhci driver do the following things: 1. When receive a remote wakeup event in irq_handler, set the resume_done value as jiffies + 20ms, and modify rh_timer to poll root hub status at that time; 2. When receive a GetPortStatus request, if the jiffies is after the resume_done value, clear the resume signal and resume_done. However, if usb_port_resume() is called before the rh_timer triggered, it will indicate the port as Suspend Cleared and skip the clear resume signal part. The device will fail the usb_get_status request in finish_port_resume(), and usbcore will try a reset-resume instead. Device will work OK after reset-resume, but resume_done value is not cleared in this case, and xhci_bus_suspend() will fail because when it finds a non-zero resume_done value, it will regard the port as resuming and return -EBUSY. This causes issue on some platforms that the system fail to suspend after remote wakeup from suspend by USB2 devices connected to xHCI port. To fix this issue, report the port status as suspend if the resume is signaling less that 20ms, and usb_port_resume() will wait 25ms and check port status again, so xHCI driver can clear the resume signaling and resume_done value. This should be backported to kernels as old as 2.6.37. Signed-off-by: Andiry Xu <andiry.xu@amd.com> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: stable@kernel.org |
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| class | ||
| core | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| otg | ||
| renesas_usbhs | ||
| serial | ||
| storage | ||
| wusbcore | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| usb-skeleton.c | ||
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 ("khubd").
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.