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The original code that resumed the USB bus on a port status change would only do so when there was a device connected to the port. If a device was just disconnected, the event would be queued for khubd, but khubd wouldn't run. That would leave the connect status change (CSC) bit set. If a USB device was plugged into that same port, the xHCI host controller would set the current connect status (CCS) bit. But since the CSC bit was already set, it would not generate an interrupt for a port status change event. That would mean the user could "Safely Remove" a device, have the bus suspend, disconnect the device, re-plug it in, and then the device would never be enumerated. Plugging in a different device on another port would cause the bus to resume, and khubd would notice the re-connected device. Running lsusb would also resume the bus, leading users to report the problem "went away" when using diagnostic tools. The solution is to resume the bus when a port status change event is received, regardless of the port status. Thank you very much to Maddog for helping me track down this Heisenbug. This patch should be queued for the 2.6.37 stable tree. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Reported-by: Jon 'maddog' Hall <maddog@li.org> Tested-by: Andiry Xu <andiry.xu@amd.com> Cc: stable@kernel.org |
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| atm | ||
| c67x00 | ||
| class | ||
| core | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| otg | ||
| 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.