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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Fei Shao <fshao@chromium.org>, Jeff LaBundy <jeff@labundy.com>,
        Douglas Anderson <dianders@chromium.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Rob Herring <robh@kernel.org>, Jiri Kosina <jkosina@suse.cz>,
        Sasha Levin <sashal@kernel.org>, dmitry.torokhov@gmail.com,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        conor+dt@kernel.org, linux-input@vger.kernel.org,
        devicetree@vger.kernel.org
Subject: [PATCH AUTOSEL 6.4 34/58] dt-bindings: input: goodix: Add "goodix,no-reset-during-suspend" property
Date:   Sun, 23 Jul 2023 21:13:02 -0400
Message-Id: <20230724011338.2298062-34-sashal@kernel.org>
In-Reply-To: <20230724011338.2298062-1-sashal@kernel.org>
References: <20230724011338.2298062-1-sashal@kernel.org>
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From: Fei Shao <fshao@chromium.org>

[ Upstream commit 359ed24a0dd3802e703ec8071dc3b6ed446de5f0 ]

We observed that on Chromebook device Steelix, if Goodix GT7375P
touchscreen is powered in suspend (because, for example, it connects to
an always-on regulator) and with the reset GPIO asserted, it will
introduce about 14mW power leakage.

To address that, we add this property to skip reset during suspend.
If it's set, the driver will stop asserting the reset GPIO during
power-down. Refer to the comments in the driver for details.

Signed-off-by: Fei Shao <fshao@chromium.org>
Suggested-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Jeff LaBundy <jeff@labundy.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 .../devicetree/bindings/input/goodix,gt7375p.yaml        | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/goodix,gt7375p.yaml b/Documentation/devicetree/bindings/input/goodix,gt7375p.yaml
index ce18d7dadae23..1edad1da1196d 100644
--- a/Documentation/devicetree/bindings/input/goodix,gt7375p.yaml
+++ b/Documentation/devicetree/bindings/input/goodix,gt7375p.yaml
@@ -43,6 +43,15 @@ properties:
       itself as long as it allows the main board to make signals compatible
       with what the touchscreen is expecting for its IO rails.
 
+  goodix,no-reset-during-suspend:
+    description:
+      Set this to true to enforce the driver to not assert the reset GPIO
+      during suspend.
+      Due to potential touchscreen hardware flaw, back-powering could happen in
+      suspend if the power supply is on and with active-low reset GPIO asserted.
+      This property is used to avoid the back-powering issue.
+    type: boolean
+
 required:
   - compatible
   - reg
-- 
2.39.2