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From:   Ioan-Adrian Ratiu <adi@adirat.com>
To:     Salvatore Bonaccorso <carnil@debian.org>,
        Alessandro Grassi <alessandro@aggro.it>,
        986561@bugs.debian.org,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Jiri Kosina <jkosina@suse.cz>
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Bug#986561: linux: Regression in drivers/hid/hid-dr.c causing
 horizontal D-pad to malfunction on SNES joystick
In-Reply-To: <YHb2Dt24465WcN1r@eldamar.lan>
References: <161779964431.889220.2857033195611862828.reportbug@malacoda>
 <YHb2Dt24465WcN1r@eldamar.lan>
Date:   Wed, 14 Apr 2021 20:17:01 +0300
Message-ID: <87o8eg946q.fsf@ryzen9.i-did-not-set--mail-host-address--so-tickle-me>
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Hi,

On Wed, 14 Apr 2021, Salvatore Bonaccorso <carnil@debian.org> 
wrote:
> Hi Ioan-Adrian, 
> 
> On Wed, Apr 07, 2021 at 02:47:24PM +0200, Alessandro Grassi 
> wrote: 
>> Source: linux Severity: normal Tags: upstream X-Debbugs-Cc: 
>> alessandro@aggro.it  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? 

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

>
> Regards,
> Salvatore