linux-kernel - [PATCH v2 3/5] arm64: dts: qcom: sc7180: Start the trogdor eDP/touchscreen regulator on

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Date:   Thu,  8 Dec 2022 18:06:10 -0800
From:   Douglas Anderson <dianders@...omium.org>
To:     Bjorn Andersson <andersson@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-arm-msm@...r.kernel.org, mka@...omium.org,
        Yunlong Jia <ecs.beijing2022@...il.com>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-input@...r.kernel.org, swboyd@...omium.org,
        Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/5] arm64: dts: qcom: sc7180: Start the trogdor eDP/touchscreen regulator on

Now that we've added the `off-on-delay-us` for the touchpanel
regulator, we can see that we're actually hitting that delay at
bootup. I saw about 200 ms of delay.

Let's avoid that delay by starting the regulator on. We'll only do
this for eDP devices for the time being.

NOTE: we _won't_ do this for homestar. Homestar's panel really likes
to be power cycled. It's why the Linux driver for this panel has a
pm_runtime_put_sync_suspend() when the panel is being unprepared but
the normal panel-edp driver doesn't. It's also why this hardware has a
separate power rail for eDP vs. touchscreen, unlike all the other
trogdor boards. We won't start homestar's regulator on. While this
could mean a slight delay on homestar, it is probably a _correct_
delay. The bootloader might have left the regulator on (it does so in
dev and recovery modes), so if we turned the regulator off at probe
time and we actually hit the delay then we were probably violating T12
in the panel spec.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
---

(no changes since v1)

 .../boot/dts/qcom/sc7180-trogdor-homestar.dtsi | 18 ++++++++++++++++++
 .../dts/qcom/sc7180-trogdor-parade-ps8640.dtsi |  8 ++++++++
 .../dts/qcom/sc7180-trogdor-ti-sn65dsi86.dtsi  |  8 ++++++++
 3 files changed, 34 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
index d3cf64c16dcd..b3ba23a88a0b 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
@@ -85,6 +85,24 @@ map1 {
 	};
 };
 
+/*
+ * ADDITIONS TO FIXED REGULATORS DEFINED IN PARENT DEVICE TREE FILES
+ *
+ * Sort order matches the order in the parent files (parents before children).
+ */
+
+&pp3300_dx_edp {
+	/*
+	 * The atna33xc20 really likes to be power cycled to keep it from
+	 * getting in a bad state. This is the reason that the touchscreen
+	 * rail and eDP rails are separate from each other on homestar (but
+	 * not other trogdor devices) Make sure it starts "off" at bootup.
+	 */
+	/delete-property/ regulator-boot-on;
+};
+
+/* ADDITIONS TO NODES DEFINED IN PARENT DEVICE TREE FILES */
+
 ap_ts_pen_1v8: &i2c4 {
 	status = "okay";
 	clock-frequency = <400000>;
diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-parade-ps8640.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-parade-ps8640.dtsi
index e27a769f8cd4..5aa7949b5328 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-parade-ps8640.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-parade-ps8640.dtsi
@@ -34,6 +34,14 @@ pp3300_brij_ps8640: pp3300-brij-ps8640-regulator {
 
 &pp3300_dx_edp {
 	off-on-delay-us = <500000>;
+
+	/*
+	 * It's nicer to start with this regulator enabled. The
+	 * bootloader may have left it on and it's nice not to cause an
+	 * extra power cycle of the touchscreen and eDP panel at bootup.
+	 * This should help speed bootup because we have off-on-delay-us.
+	 */
+	regulator-boot-on;
 };
 
 /* ADDITIONS TO NODES DEFINED IN PARENT DEVICE TREE FILES */
diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-ti-sn65dsi86.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-ti-sn65dsi86.dtsi
index 3188788306d0..e52b8776755d 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-ti-sn65dsi86.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-ti-sn65dsi86.dtsi
@@ -15,6 +15,14 @@
 
 &pp3300_dx_edp {
 	off-on-delay-us = <500000>;
+
+	/*
+	 * It's nicer to start with this regulator enabled. The
+	 * bootloader may have left it on and it's nice not to cause an
+	 * extra power cycle of the touchscreen and eDP panel at bootup.
+	 * This should help speed bootup because we have off-on-delay-us.
+	 */
+	regulator-boot-on;
 };
 
 /* ADDITIONS TO NODES DEFINED IN PARENT DEVICE TREE FILES */
-- 
2.39.0.rc1.256.g54fd8350bd-goog