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Date:   Tue, 31 Oct 2023 03:23:38 +0100 (GMT+01:00)
From:   =?UTF-8?Q?Thomas_Wei=C3=9Fschuh_?= <thomas@t-8ch.de>
To:     Anshul Dalal <anshulusr@gmail.com>
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        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Jeff LaBundy <jeff@labundy.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-kernel@vger.kernel.org
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References: <20231027051819.81333-1-anshulusr@gmail.com> <20231027051819.81333-2-anshulusr@gmail.com> <d1dd2142-546f-42b7-8966-ab75fd4f8817@t-8ch.de> <efea5ae2-7e41-4b78-a283-1f907be560b0@gmail.com>
Subject: Re: [PATCH v6 2/2] input: joystick: driver for Adafruit Seesaw
 Gamepad
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Oct 31, 2023 03:10:50 Anshul Dalal <anshulusr@gmail.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 Wei=C3=9Fschuh 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 {
>>> +=C2=A0=C2=A0 unsigned int code;
>>> +=C2=A0=C2=A0 unsigned int bit;
>>> +};
>>> +
>>> +static const struct seesaw_button_description seesaw_buttons[] =3D {
>>> +=C2=A0=C2=A0 {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .code =3D BTN_EAST,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bit =3D SEESAW_BUTTON_A,
>>> +=C2=A0=C2=A0 },
>>> +=C2=A0=C2=A0 {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .code =3D BTN_SOUTH,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bit =3D SEESAW_BUTTON_B,
>>> +=C2=A0=C2=A0 },
>>> +=C2=A0=C2=A0 {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .code =3D BTN_NORTH,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bit =3D SEESAW_BUTTON_X,
>>> +=C2=A0=C2=A0 },
>>> +=C2=A0=C2=A0 {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .code =3D BTN_WEST,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bit =3D SEESAW_BUTTON_Y,
>>> +=C2=A0=C2=A0 },
>>> +=C2=A0=C2=A0 {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .code =3D BTN_START,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bit =3D SEESAW_BUTTON_START,
>>> +=C2=A0=C2=A0 },
>>> +=C2=A0=C2=A0 {
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .code =3D BTN_SELECT,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 .bit =3D SEESAW_BUTTON_SELECT,
>>> +=C2=A0=C2=A0 },
>>> +};
>>
>> 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[] =3D {
> =C2=A0=C2=A0=C2=A0 {KE_KEY, SEESAW_BUTTON_A, {BTN_SOUTH}},
> =C2=A0=C2=A0=C2=A0 {KE_KEY, SEESAW_BUTTON_B, {BTN_EAST}},

No braces I think.

> =C2=A0=C2=A0=C2=A0 ...
> };
>
> for (i =3D 0; i < ARRAY_SIZE(seesaw_buttons_new); i++) {
> =C2=A0=C2=A0=C2=A0 sparse_keymap_report_entry(input, &seesaw_buttons_new[=
i],
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 data.button_state & BIT(seesaw=
_buttons_new[i].code),
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 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