Bug#986561: linux: Regression in drivers/hid/hid-dr.c causing horizontal D-pad to malfunction on SNES joystick

[Salvatore Bonaccorso]

Hi Ioan-Adrian,

Source: linux
Severity: normal
Tags: upstream
Greetings,
I am encountering the issue described in this thread[1], using a gamepad identified as "DragonRise" with USB ID 0079:0011.
The joypad works as intended except for the D-pad: up and down are detected in jstest (though misinterpreted: the input graph shows the points in the left up/down corners instead of the center), the left and right buttons are completely ignored.
Running 'input-events' shows events 0/127 and 255/127 on up and down respectively, nothing at all on left and right.
I was able to identify that the misbehaviour was caused by this commit[2] on the kernel source tree. To determine this I have rebuilt the Debian kernel using hid-dr.c from the previous commit[3] and loaded hid-dr.ko manually, with which the gamepad worked as intended. I have replaced the file again with the one from the breaking commit iself ([2]) and the behaviour was again broken.
Furthermore, to confirm that that was the breaking commit, I have commented line 315 (the input mapping one in the struct) from the current Debian source tree and rebuilt it, the joypad works as it should.
Regards,
Alessandro
[1]: https://retropie.org.uk/forum/topic/25657/controler-issue-no-left-and-right-not-working-at-all
[2]: https://github.com/torvalds/linux/commit/e15944099870f374ca7efc62f98cf23ba272ef43
[3]: https://github.com/torvalds/linux/commit/313726cad3b68039c8e4dcad5a2840a0d375678c

A user in Debian reported that e15944099870 ("HID: hid-dr: add input
mapping for axis selection") introduced a regression, described above.

Does this ring some bell to you?

Regards,
Salvatore

[Ioan-Adrian Ratiu]

Hi,

Post by Salvatore Bonaccorso
Hi Ioan-Adrian,
On Wed, Apr 07, 2021 at 02:47:24PM +0200, Alessandro Grassi

described in this thread[1], using a gamepad identified as
"DragonRise" with USB ID 0079:0011. The joypad works as
intended except for the D-pad: up and down are detected in
jstest (though misinterpreted: the input graph shows the points
in the left up/down corners instead of the center), the left
and right buttons are completely ignored. Running
'input-events' shows events 0/127 and 255/127 on up and down
respectively, nothing at all on left and right. I was able to
identify that the misbehaviour was caused by this commit[2] on
the kernel source tree. To determine this I have rebuilt the
Debian kernel using hid-dr.c from the previous commit[3] and
loaded hid-dr.ko manually, with which the gamepad worked as
intended. I have replaced the file again with the one from the
breaking commit iself ([2]) and the behaviour was again broken.
Furthermore, to confirm that that was the breaking commit, I
have commented line 315 (the input mapping one in the struct)
from the current Debian source tree and rebuilt it, the joypad
https://retropie.org.uk/forum/topic/25657/controler-issue-no-left-and-right-not-working-at-all
https://github.com/torvalds/linux/commit/e15944099870f374ca7efc62f98cf23ba272ef43
https://github.com/torvalds/linux/commit/313726cad3b68039c8e4dcad5a2840a0d375678c

A user in Debian reported that e15944099870 ("HID: hid-dr: add
input mapping for axis selection") introduced a regression,
described above.
Does this ring some bell to you?

Unfortunately no and I do not have the HW to test anymore.

It is possible that change introduced a regression on newer
"DragonRise" gamepads and maybe that mapping logic needs to be a
bit more complex, depending on the HW differences.

Sorry I can't be more helpful,
Adrian

Post by Salvatore Bonaccorso
Regards,
Salvatore