linux-kernel - Re: [PATCH 7/7] arm64: dts: qcom: sc7280: Hook up the touchscreen IO rail on evoker

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Message-ID: <Y+KcxxWzm0PFksm+@google.com>
Date:   Tue, 7 Feb 2023 18:47:35 +0000
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        devicetree@...r.kernel.org, Stephen Kitt <steve@....org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andy Gross <agross@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/7] arm64: dts: qcom: sc7280: Hook up the touchscreen IO
 rail on evoker

On Mon, Feb 06, 2023 at 06:48:16PM -0800, Douglas Anderson wrote:
> On older revisions of evoker, the touchscreen was either
> non-functional or needed special hardware magic to get it talking
> properly. It's been decided that the proper way going forward is to
> use L3C to power some buffers on the QCard and then configure the
> touchscreens for 1.8V. Let's do that.
> 
> Note that this is safe to do even on older revs even if it might not
> make the touchscreen work there (because they didn't have a properly
> stuffed QCard). As talked about in the patch ("arm64: dts: qcom:
> sc7280: On QCard, regulator L3C should be 1.8V") the L3C regulator
> didn't go anywhere at all on older revs.
> 
> This patch relies on the patch ("HID: i2c-hid: goodix: Add
> mainboard-vddio-supply") in order to function properly. Without that
> patch this one won't do any harm but it won't actually accomplish its
> goal.
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Reviewed-by: Matthias Kaehlcke <mka@...omium.org>