On Tue, 7 Jan 2025 14:29:35 +0200, Mathias Nyman wrote:
>Does disabling USB2 hardware LPM for the device make it work again?
>
>Adding USB_QUIRK_NO_LPM quirk "k" for your device vid:pid should do it.
>i.e. add "usbcore.quirks=0fce:0dde:k" parameter to your kernel cmdline.
That fixed my test case on Debian kernel 6.12.8-amd64, which is among those
that have been failing.
>Or alternatively disable usb2 lpm during runtime via sysfs
>(after enumeration, assuming device is "1-3" as in the log):
># echo 0 > /sys/bus/usb/devices/1-3/power/usb2_hardware_lpm
That did not fix it. Maybe it's too late once the device is connected and
enumerated?
>If those work then we need to figure out if we incorrectly try to enable
>USB2 hardware LPM, or if device just can't handle LPM even if it claims
>to be LPM capable.
>
>Host hardware LPM capability can be checked from xhci reg-ext-protocol
>fields from debugfs.
>cat /sys/kernel/debug/usb/xhci/0000:0c:00.0/reg-ext-protocol:*
>(please print content of _all_ reg_ext_protocol* files, LPM capability is
>bit 19 of EXTCAP_PORTINFO)
# cd /sys/kernel/debug/usb/xhci/0000:0c:00.0/
# grep . reg-ext-protocol:*
reg-ext-protocol:00:EXTCAP_REVISION = 0x03200802
reg-ext-protocol:00:EXTCAP_NAME = 0x20425355
reg-ext-protocol:00:EXTCAP_PORTINFO = 0x40000101
reg-ext-protocol:00:EXTCAP_PORTTYPE = 0x00000000
reg-ext-protocol:00:EXTCAP_MANTISSA1 = 0x00050134
reg-ext-protocol:00:EXTCAP_MANTISSA2 = 0x000a4135
reg-ext-protocol:00:EXTCAP_MANTISSA3 = 0x000a4136
reg-ext-protocol:00:EXTCAP_MANTISSA4 = 0x00144137
reg-ext-protocol:01:EXTCAP_REVISION = 0x03100802
reg-ext-protocol:01:EXTCAP_NAME = 0x20425355
reg-ext-protocol:01:EXTCAP_PORTINFO = 0x20000402
reg-ext-protocol:01:EXTCAP_PORTTYPE = 0x00000000
reg-ext-protocol:01:EXTCAP_MANTISSA1 = 0x00050134
reg-ext-protocol:01:EXTCAP_MANTISSA2 = 0x000a4135
reg-ext-protocol:02:EXTCAP_REVISION = 0x02000802
reg-ext-protocol:02:EXTCAP_NAME = 0x20425355
reg-ext-protocol:02:EXTCAP_PORTINFO = 0x00190c06
reg-ext-protocol:02:EXTCAP_PORTTYPE = 0x00000000
# grep EXTCAP_PORTINFO reg-ext-protocol:*
reg-ext-protocol:00:EXTCAP_PORTINFO = 0x40000101
reg-ext-protocol:01:EXTCAP_PORTINFO = 0x20000402
reg-ext-protocol:02:EXTCAP_PORTINFO = 0x00190c06
>>> bool(0x40000101 & 1 << 19)
False
>>> bool(0x20000402 & 1 << 19)
False
>>> bool(0x00190c06 & 1 << 19)
True
>Device USB2 LPM capability can be checked from the devices BOS descriptor,
>visible (as sudo/root) with lsusb -v -d 0fce:0dde
# lsusb -v -d 0fce:0dde |grep -B 5 LPM
USB 2.0 Extension Device Capability:
bLength 7
bDescriptorType 16
bDevCapabilityType 2
bmAttributes 0x00000006
BESL Link Power Management (LPM) Supported
I think that says the device claims support for LPM, yes?
Maybe relevant: The failing test and lsusb were both run with the device in
fastboot mode, which allows talking to the bootloader. Is it possible that a
device would support LPM in normal operating modes, but not in bootloader
mode, yet present the same capabilities data structure in both modes?
