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

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
To: Chen-Yu Tsai <wenst@chromium.org>
Cc: Doug Anderson <dianders@chromium.org>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Wolfram Sang <wsa@kernel.org>, Benson Leung <bleung@chromium.org>,
	Tzung-Bi Shih <tzungbi@kernel.org>,
	chrome-platform@lists.linux.dev, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
	Johan Hovold <johan@kernel.org>,
	Hsin-Yi Wang <hsinyi@chromium.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	andriy.shevchenko@linux.intel.com, Jiri Kosina <jikos@kernel.org>,
	linus.walleij@linaro.org, broonie@kernel.org,
	gregkh@linuxfoundation.org, hdegoede@redhat.com,
	james.clark@arm.com, james@equiv.tech, keescook@chromium.org,
	rafael@kernel.org, tglx@linutronix.de,
	Jeff LaBundy <jeff@labundy.com>,
	linux-input@vger.kernel.org, linux-i2c@vger.kernel.org
Subject: Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail
Date: Wed, 6 Dec 2023 11:02:30 +0100	[thread overview]
Message-ID: <4b9ea82c-d1a4-47b6-ba03-346cfdedef05@collabora.com> (raw)
In-Reply-To: <CAGXv+5G5fFTv8zn=YamSdccjuYemE5oKBqjb8CSyGzu9aMJ0eg@mail.gmail.com>

Il 06/12/23 03:55, Chen-Yu Tsai ha scritto:
> On Tue, Dec 5, 2023 at 6:22 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@collabora.com> wrote:
>>
>> 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.
> 
> I think this should be migrated to use the proper GPIO bindings: the
> GPIO_PULL_UP / GPIO_PULL_DOWN / GPIO_BIAS_DISABLE flags.
> 
> But that's a different discussion.
> 

100% agreed.

Cheers,
Angelo