Comment 0 for bug 1935846

The hid-sony driver has custom DS4 connect/disconnect logic for the
DS4 dongle, which is a USB dongle acting as a proxy to Bluetooth
connected DS4.

The connect/disconnect logic works fine generally, however not in
conjunction with Steam. Steam implements its own DS4 driver using
hidraw. Both hid-sony and Steam are issuing their own HID requests
and are racing each other during DS4 dongle connect/disconnect
resulting in a kernel crash in hid-sony.

The problem is that upon a DS4 connect to the dongle, hid-sony kicks
of 'ds4_get_calibration_data' from within its dongle hotplug code.
The calibration code issues raw HID feature report for reportID 0x02.
When Steam is running, it issues a feature report for reportID 0x12
typically just prior to hid-sony requesting feature reportID 0x02.
The result is that 'ds4_get_calibration_data' receives the data Steam
requested as that's the HID report returing first. Currently this
results in it processing invalid data, which ultimately results in a
divide by zero upon a future 'dualshock4_parse_report'.

The solution for now is to check within 'ds4_get_calibration_data' to
check if we received data for the feature report we issued and if not
retry.

Please consider to add this patch to Ubuntu LTS kernels.

Commit:
https://github.com/torvalds/linux/commit/f5dc93b7875bcb8be77baa792cc9432aaf65365b