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From:   Fei Shao <fshao@chromium.org>
To:     Jiri Kosina <jikos@kernel.org>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Jeff LaBundy <jeff@labundy.com>,
        Douglas Anderson <dianders@chromium.org>,
        Fei Shao <fshao@chromium.org>, Rob Herring <robh@kernel.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        devicetree@vger.kernel.org, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH RESEND v4 1/2] dt-bindings: input: goodix: Add "goodix,no-reset-during-suspend" property
Date:   Wed, 24 May 2023 11:42:36 +0800
Message-ID: <20230524114233.RESEND.v4.1.Idaa807e609fb3c322b96209c50f71d260917c7be@changeid>
In-Reply-To: <20230524114233.RESEND.v4.2.I424e840ae6de3cdbd67394cf4efd24534f6434ba@changeid>
References: <20230524114233.RESEND.v4.2.I424e840ae6de3cdbd67394cf4efd24534f6434ba@changeid>
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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>


---

Changes in v4:
- Rebase on top of next-20230523
- Collect the review tags

Changes in v2:
- Use a more accurate property name and with "goodix," prefix

 .../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 ce18d7dadae2..1edad1da1196 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
-- 
2.40.1.698.g37aff9b760-goog