linux-kernel - Re: [PATCH v2 3/4] arm64: dts: qcom: x1e80100-crd: Fix backlight

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Message-ID: <ZpUXNmrs2nfViUeP@hovoldconsulting.com>
Date: Mon, 15 Jul 2024 14:33:58 +0200
From: Johan Hovold <johan@...nel.org>
To: Stephan Gerhold <stephan.gerhold@...aro.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Jessica Zhang <quic_jesszhan@...cinc.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Douglas Anderson <dianders@...omium.org>,
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	Abel Vesa <abel.vesa@...aro.org>
Subject: Re: [PATCH v2 3/4] arm64: dts: qcom: x1e80100-crd: Fix backlight

On Mon, Jul 15, 2024 at 02:15:39PM +0200, Stephan Gerhold wrote:
> The backlight does not work correctly with the current display panel
> configuration: It works after boot, but once the display gets disabled it
> is not possible to get it back on. It turns out that the ATNA45AF01 panel
> needs exactly the same non-standard power sequence as implemented by the
> panel-samsung-atna33xc20 driver for sc7180-trogdor-homestar.
> 
> Switch the panel in the DT to the new compatible and make two more changes
> to make it work correctly:
> 
>  1. Add the missing GPIO for the panel EL_ON3 line (EDP_BL_EN on CRD and
>     enable-gpios in the DT).
>  2. Drop the regulator-always-on for the panel regulator. The panel does
>     not seem to power off properly if the regulator stays on.
> 
> Fixes: d7e03cce0400 ("arm64: dts: qcom: x1e80100-crd: Enable more support")
> Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> Signed-off-by: Stephan Gerhold <stephan.gerhold@...aro.org>
> ---
> This can be applied as fix for 6.11 since the driver works as-is with the
> fallback compatible. If so, the defconfig patch should ideally also go
> there to ensure people actually have the driver enabled.

Verified that I can change the brightness setting and that the backlight
comes on again after being turned off (e.g. at suspend):

Reviewed-by: Johan Hovold <johan+linaro@...nel.org>
Tested-by: Johan Hovold <johan+linaro@...nel.org>