On Tue, 18 Aug 2020, Marius Zachmann wrote: > > > Possibly because of the changes in usbhid/hid-core.c the first > > > raw input report is not received during ccp_probe function and it will > > > timeout. I am not sure, whether this behaviour is expected after > > > hid_device_io_start or if I am missing something. > > > As a solution this adds msleep(50) to ccp_probe so that all initial > > > input reports can be received. > > > > > > Signed-off-by: Marius Zachmann <mail@xxxxxxxxxxxxxxxxx> > > > > Let's just ask the HID maintainers. Is this expected, and the correct fix ? > > This seems to be a problem with "HID: usbhid: do not sleep when opening > device". There is a bug report with some Logitech devices at the correct > thread. These drivers also use hid_device_io_start and fail. Seems to me, > this is the same problem and I retract this (not so beautiful) fix until > this is sorted out. [ CCing Dmitry ] Yeah, this problem popped out also in other contexts, where many Logitech devices didn't probe properly, because of the race where the first IRQ is dropped on the floor (after hid_device_io_start() happens, but before the 50ms timeout passess), and report descriptor never gets parsed and populated. As this is just a boot time micro-optimization, I am going to revert the patch for 5.9 now, and we can try to fix this properly for next merge window. Thanks, -- Jiri Kosina SUSE Labs
