** Also affects: linux-intel (Ubuntu)
Importance: Undecided
Status: New
** Changed in: linux-intel (Ubuntu Hirsute)
Status: New => Invalid
** Changed in: linux-intel (Ubuntu Focal)
Assignee: (unassigned) => Jesse Sung (wenchien)
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https://bugs.launchpad.net/bugs/1939638
Title:
[regression] USB device is not detected during boot
Status in HWE Next:
New
Status in linux package in Ubuntu:
New
Status in linux-intel package in Ubuntu:
New
Status in linux source package in Focal:
Fix Committed
Status in linux-intel source package in Focal:
New
Status in linux source package in Hirsute:
Fix Committed
Status in linux-intel source package in Hirsute:
Invalid
Bug description:
[SRU Justification]
[Impact]
The USB devices (keyboard, storage...) are failed to be detected when
connecting to the problematic root hubs which need longer PowerOn-to-PowerGood
delay than it claims in the hub descriptor. It's caused by the upstream fix
90d28fb53d4a ("usb: core: reduce power-on-good delay time of root hub").
[Fix]
Reverting the upstream fix until a formal fix been placed.
[Test Case]
1. Plug the USB device to the ports of problematic root hub.
2. Power on the machine.
3. Check if the USB device can work or not after boot.
[Regression Potential]
Low. The longer delay is proven safe in old kernels.
========== Original Bug Description ==========
[Summary]
The USB devices (keyboard, storage...) are failed to be detected during boot
after upgrade to UBUNTU focal kernel 5.4.0-78 and hirsute 5.11.0-26. However,
they will be detected and working ok after re-plugging. The kernel output shows
as down below during boot
[ 39.350435] hub 1-0:1.0: USB hub found
[ 39.398835] hub 1-0:1.0: 12 ports detected
[ 39.622744] usb usb1-port3: couldn't allocate usb_device
And when I plug out then plug in the same device, it shows
[57210.794140] usb 1-3: new low-speed USB device number 4 using xhci_hcd
[57210.951289] usb 1-3: New USB device found, idVendor=17ef, idProduct=6099,
bcdDevice= 1.14
[57210.951293] usb 1-3: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
After doing kernel bisecting, we found the upstream commit
https://github.com/torvalds/linux/commit/90d28fb53d4a51299ff324dede015d5cb11b88a2
makes the difference. It indicates that the delay for the root hub from
power_on to power_good is not long enough. There was no problem if the delay is
100 ms. From the Hub Descriptor of the root hub, the value is 10 * 2
milliseconds. And the XHCI spec also says in section 5.4.8
"""
The host is required to have power stable to the port within 20 milliseconds
of the '0' to '1' transition of PP. If PPC = '1', software is responsible for
waiting 20ms.
"""
The commit seems to follow the SPEC but could cause problems on some
hubs.
[Reproduce Steps]
1. Plug the USB device to the physical port #1 and #4 which belongs to
high-speed hub.
2. Power on the machine.
3. Check if the USB device can work or not after boot.
[Results]
Expected:
All usb devices connect to the hub should work OK.
Actual:
USB devices connects to high-speed hub can not be probed.
[Additional Information]
Kernel Version: focal 5.4.0-78 and hirsute 5.11.0-26
[Upstream bug]
https://bugzilla.kernel.org/show_bug.cgi?id=214021
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