linux-kernel - Re: [PATCH 2/2] hid-sony: DS3: Report analog buttons for Sixaxis

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Message-ID: <ec4d07de-4944-a7ea-2b74-c4162af75b16@enpas.org>
Date:   Wed, 30 Aug 2023 00:53:51 +0900
From:   Max Staudt <max@...as.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Vicki Pfau <vi@...rift.com>, Pavel Rojtberg <rojtberg@...il.com>,
        Roderick Colenbrander <roderick@...kai.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] hid-sony: DS3: Report analog buttons for Sixaxis

On 8/27/23 00:21, Max Staudt wrote:
> This change exposes these buttons as axes in a way that is as backwards
> compatible and as close to the Linux gamepad spec as possible.
> 
> [...]
> 
>   - The D-Pad as ABS_HAT0X/ABS_HAT0Y, -255 to 255

One further idea:

The DualShock 3 reports all 4 D-pad buttons separately, and hid-sony currently reports them as discrete digital buttons to userspace.

Would it be better to do the same with the analog buttons, i.e. to report the 4 measurements as discrete axes, rather than the current patch's approach of merging them into two logical axes?

Of course, this would require 4 more axes, this would not fit into any existing scheme, and since we've run out of ABS_MISC+n at this point, this could be a further reason for officially reserving a range of axes for analog buttons. Something like:

#define ABS_BTN_SOUTH		0x40
#define ABS_BTN_A		ABS_BTN_SOUTH
#define ABS_BTN_EAST		0x41
#define ABS_BTN_B		ABS_BTN_EAST
#define ABS_BTN_C		0x42
#define ABS_BTN_NORTH		0x43
#define ABS_BTN_X		ABS_BTN_NORTH
#define ABS_BTN_WEST		0x44
#define ABS_BTN_Y		ABS_BTN_WEST
#define ABS_BTN_Z		0x45

#define ABS_BTN_DPAD_UP		0x46
#define ABS_BTN_DPAD_DOWN	0x47
#define ABS_BTN_DPAD_LEFT	0x48
#define ABS_BTN_DPAD_RIGHT	0x49

#define ABS_MAX			0x4f
#define ABS_CNT			(ABS_MAX+1)

Max