On 7/30/20 11:54 PM, Swyter wrote:

On 31/07/2020 8:33, Cameron Gutman wrote:

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While doing my research I also noticed that the 1532:0037 VID/PID seems to
be used by the DeathAdder 2013, so that Razer Sabertooth instance looks
wrong and very suspect to me, I created a separate patch for that.

The above sentence probably doesn't belong in the commit message.

Fair enough, I should probably turn that into "reviewer" notes.
I think I mentioned it because I didn't update that bad entry.

Thinking it would be deleted soon. But good point.

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The docs and comment changes look fine to me.

Great, I was a bit wary about this.

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I'm somewhat concerned about the possibility of breaking userspace by changing
names. Some programs' gamepad mappings may be dependent on matching the device
names, rather than the VID+PID.

For example, Android did not expose the VID and PID for input devices until
Android 4.4. The device name was the only available attribute for matching
gamepads from Android 2.3 to 4.3. While these ancient Android version will
almost certainly never run a kernel with this patch, I worry about the
possibility of apps that haven't moved to VID+PID matching (and not just for
Android; I don't know if other libraries or frameworks have/had similar
limitations).

Perhaps my concerns are overblown, but If we aren't worried about changing
names, I'd really prefer to just drop the hardcoded names entirely and use the
manufacturer and product strings provided in the USB string descriptors. The
device list would turn into a quirk list where only device entries with a
special mapping flag like MAP_DPAD_TO_BUTTONS or MAP_TRIGGERS_TO_BUTTONS would
remain, and the device name strings would just become comments on each quirk
entry.

Thoughts?




Regards,
Cameron

I don't doubt that changing some names will break some basic rule matching.

But given that the kernel nomenclature is so inconsistent, I think anyone searching
for "X-Box" and five other variants will also have to search for the actual "Xbox",
or at least I hope so. Keep in mind that I have tried to make each overhauled entry
*more* detailed when possible. So now each model has extra information (mainly
manufacturer and button-layout type) instead only some vague/informal model name.

SDL2 and Unity abstract these things a bit. I actually implement similar strings
checks in my own game/engine as fallback and it's exactly what I ended up doing.

I generally don't trust device strings, they'll be less detailed than these.
A good bunch of those are unlicensed, so they'll be wrong or missing.

Let me know what you think.

I agree that the changes look like an improvement. I also doubt that we'll ever
be able to prove definitively that there aren't programs out that taking a
dependency on the exact names of the gamepads in the list.

I guess one could also make the argument that adding a gamepad to this list
would have the same effect of possibly breaking userspace programs that used to
identify it via the "Generic X-box Pad" string. Those programs would need to
have the flexibility to handle receiving the generic name or a specific name
from our list, so maybe they're already robust enough to handle not matching on
one of the names they're expecting.

Dmitry, what are your thoughts about possible userspace breakage from updating
input device names? Has a similar change been done successfully before?


Regards,
Cameron