linux-kernel - [PATCH] drm/panel: atna33xc20: Fix unbalanced regulator in the case HPD doesn't assert

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Date: Wed, 13 Mar 2024 14:12:14 -0700
From: Douglas Anderson via B4 Relay <devnull+dianders.chromium.org@...nel.org>
To: Neil Armstrong <neil.armstrong@...aro.org>, 
 Jessica Zhang <quic_jesszhan@...cinc.com>, Sam Ravnborg <sam@...nborg.org>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Douglas Anderson <dianders@...omium.org>
Subject: [PATCH] drm/panel: atna33xc20: Fix unbalanced regulator in the
 case HPD doesn't assert

From: Douglas Anderson <dianders@...omium.org>

When the atna33xc20 driver was first written the resume code never
returned an error. If there was a problem waiting for HPD it just
printed a warning and moved on. This changed in response to review
feedback [1] on a future patch but I accidentally didn't account for
rolling back the regulator enable in the error cases. Do so now.

[1] https://lore.kernel.org/all/5f3cf3a6-1cc2-63e4-f76b-4ee686764705@linaro.org/

Fixes: 3b5765df375c ("drm/panel: atna33xc20: Take advantage of wait_hpd_asserted() in struct drm_dp_aux")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
 drivers/gpu/drm/panel/panel-samsung-atna33xc20.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c b/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c
index 76c2a8f6718c..9c336c71562b 100644
--- a/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c
+++ b/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c
@@ -109,19 +109,17 @@ static int atana33xc20_resume(struct device *dev)
 		if (hpd_asserted < 0)
 			ret = hpd_asserted;
 
-		if (ret)
+		if (ret) {
 			dev_warn(dev, "Error waiting for HPD GPIO: %d\n", ret);
-
-		return ret;
-	}
-
-	if (p->aux->wait_hpd_asserted) {
+			goto error;
+		}
+	} else if (p->aux->wait_hpd_asserted) {
 		ret = p->aux->wait_hpd_asserted(p->aux, HPD_MAX_US);
 
-		if (ret)
+		if (ret) {
 			dev_warn(dev, "Controller error waiting for HPD: %d\n", ret);
-
-		return ret;
+			goto error;
+		}
 	}
 
 	/*
@@ -133,6 +131,12 @@ static int atana33xc20_resume(struct device *dev)
 	 * right times.
 	 */
 	return 0;
+
+error:
+	drm_dp_dpcd_set_powered(p->aux, false);
+	regulator_disable(p->supply);
+
+	return ret;
 }
 
 static int atana33xc20_disable(struct drm_panel *panel)

---
base-commit: b33651a5c98dbd5a919219d8c129d0674ef74299
change-id: 20240311-homestarpanel-regulator-f4b890ff4b7c

Best regards,
-- 
Douglas Anderson <dianders@...omium.org>