linux-kernel - Re: [PATCH v6 2/2] input: joystick: driver for Adafruit Seesaw Gamepad

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Message-ID: <9c9f6171-f879-46f5-81d2-6764257a49eb@t-8ch.de>
Date:   Tue, 31 Oct 2023 03:23:38 +0100 (GMT+01:00)
From:   Thomas Weißschuh  <thomas@...ch.de>
To:     Anshul Dalal <anshulusr@...il.com>
Cc:     Thomas Weißschuh <linux@...ssschuh.net>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jeff LaBundy <jeff@...undy.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/2] input: joystick: driver for Adafruit Seesaw
 Gamepad

Oct 31, 2023 03:10:50 Anshul Dalal <anshulusr@...il.com>:

> Hello Thomas,
>
> Thanks for the review! The requested changes will be addressed in the
> next patch version though I had a few comments below:
>
> On 10/27/23 11:44, Thomas Weißschuh wrote:
>> Hi Anshul,
>>
>> thanks for the reworks!
>>
>> Some more comments inline.
>>
>> On 2023-10-27 10:48:11+0530, Anshul Dalal wrote:

[..]

>>> +struct seesaw_button_description {
>>> +   unsigned int code;
>>> +   unsigned int bit;
>>> +};
>>> +
>>> +static const struct seesaw_button_description seesaw_buttons[] = {
>>> +   {
>>> +       .code = BTN_EAST,
>>> +       .bit = SEESAW_BUTTON_A,
>>> +   },
>>> +   {
>>> +       .code = BTN_SOUTH,
>>> +       .bit = SEESAW_BUTTON_B,
>>> +   },
>>> +   {
>>> +       .code = BTN_NORTH,
>>> +       .bit = SEESAW_BUTTON_X,
>>> +   },
>>> +   {
>>> +       .code = BTN_WEST,
>>> +       .bit = SEESAW_BUTTON_Y,
>>> +   },
>>> +   {
>>> +       .code = BTN_START,
>>> +       .bit = SEESAW_BUTTON_START,
>>> +   },
>>> +   {
>>> +       .code = BTN_SELECT,
>>> +       .bit = SEESAW_BUTTON_SELECT,
>>> +   },
>>> +};
>>
>> This looks very much like a sparse keymap which can be implemented with
>> the helpers from <linux/input/sparse-keymap.h>.
>>
>
> When going through the API provided by sparse-keymap, I could only see
> the use for sparse_keymap_report_entry here. Which leads to the
> following refactored code:
>
> static const struct key_entry seesaw_buttons_new[] = {
>     {KE_KEY, SEESAW_BUTTON_A, {BTN_SOUTH}},
>     {KE_KEY, SEESAW_BUTTON_B, {BTN_EAST}},

No braces I think.

>     ...
> };
>
> for (i = 0; i < ARRAY_SIZE(seesaw_buttons_new); i++) {
>     sparse_keymap_report_entry(input, &seesaw_buttons_new[i],
>         data.button_state & BIT(seesaw_buttons_new[i].code),
>         false);
> }
>
> I don't think this significantly improves the code unless you had some
> other way to use the API in mind.

I thought about sparse_keymap_setup() and sparse_keymap_report_event().

It does not significantly change the code but would be a standard API.

Thomas