Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 04/12/23 17:50, Doug Anderson ha scritto:
> Hi,
> 
> On Sun, Dec 3, 2023 at 10:59 PM Chen-Yu Tsai <wenst@chromium.org> wrote:
>>
>> On Sat, Dec 2, 2023 at 8:58 AM Doug Anderson <dianders@chromium.org> wrote:
>>>
>>> Hi,
>>>
>>> On Tue, Nov 28, 2023 at 12:45 AM Chen-Yu Tsai <wenst@chromium.org> wrote:
>>>>
>>>> @@ -44,6 +46,7 @@ trackpad2: trackpad@2c {
>>>>                  reg = <0x2c>;
>>>>                  hid-descr-addr = <0x0020>;
>>>>                  wakeup-source;
>>>> +               status = "fail-needs-probe";
>>>
>>> While doing this, you could also remove the hack where the trackpad
>>> IRQ pinctrl is listed under i2c4.
>>
>> Sure. I do think we can do away with it though. According to at least one
>> schematic, the interrupt line has pull-ups on both sides of the voltage
>> shifter.
>>
>> BTW, The touchscreen doesn't have pinctrl entries. This has pull-ups on
>> both sides of the voltage shifter as well.
> 
> I dunno if the convention is different on Mediatek boards, but at
> least on boards I've been involved with in the past we've always put
> pinctrl entries just to make things explicit. This meant that we
> didn't rely on the firmware/bootrom/defaults to leave pulls in any
> particular state. ...otherwise those external pull-ups could be
> fighting with internal pull-downs, right?
> 

MediaTek boards aren't special and there's no good reason for those to rely on
firmware/bootrom/defaults - so there is no good reason to avoid declaring any
relevant pinctrl entry.

Cheers,
Angelo