linux-kernel - [PATCH] drm/bridge: fix anx6345 power up sequence

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Message-ID: <20220417181538.57fa1303@blackhole>
Date:   Sun, 17 Apr 2022 18:15:38 +0200
From:   Torsten Duwe <duwe@....de>
To:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Thierry Reding <treding@...dia.com>,
        Lyude Paul <lyude@...hat.com>, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Harald Geyer <harald@...ib.org>,
        stable@...r.kernel.org, Vasily Khoruzhick <anarsoul@...il.com>
Subject: [PATCH] drm/bridge: fix anx6345 power up sequence

Align the power-up sequence with the known-good procedure documented in [1]:
un-swap dvdd12 and dvdd25, and allow a little extra time for them to settle
before de-asserting reset.
Fixes: 6aa192698089b ("drm/bridge: Add Analogix anx6345 support")

[1] https://github.com/OLIMEX/DIY-LAPTOP/blob/master/
HARDWARE/A64-TERES/TERES-PCB1-A64-MAIN/Rev.C/TERES_PCB1-A64-MAIN_Rev.C.pdf
(page 5, blue comment down left)

Reported-by: Harald Geyer <harald@...ib.org>
Signed-off-by: Torsten Duwe <duwe@....de>
Cc: stable@...r.kernel.org

---

This fixes the problem that e.g. X screensaver turns the screen black,
and it stays black until the next reboot; definitely on the Teres-I,
probably on the pinebook64, too.

--- a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
@@ -309,27 +309,27 @@ static void anx6345_poweron(struct anx63
 	gpiod_set_value_cansleep(anx6345->gpiod_reset, 1);
 	usleep_range(1000, 2000);
 
-	err = regulator_enable(anx6345->dvdd12);
+	err = regulator_enable(anx6345->dvdd25);
 	if (err) {
-		DRM_ERROR("Failed to enable dvdd12 regulator: %d\n",
+		DRM_ERROR("Failed to enable dvdd25 regulator: %d\n",
 			  err);
 		return;
 	}
 
-	/* T1 - delay between VDD12 and VDD25 should be 0-2ms */
+	/* T1 - delay between VDD25 and VDD12 should be 0-2ms */
 	usleep_range(1000, 2000);
 
-	err = regulator_enable(anx6345->dvdd25);
+	err = regulator_enable(anx6345->dvdd12);
 	if (err) {
-		DRM_ERROR("Failed to enable dvdd25 regulator: %d\n",
+		DRM_ERROR("Failed to enable dvdd12 regulator: %d\n",
 			  err);
 		return;
 	}
 
 	/* T2 - delay between RESETN and all power rail stable,
-	 * should be 2-5ms
+	 * should be at least 2-5ms, 10ms to be safe.
 	 */
-	usleep_range(2000, 5000);
+	usleep_range(9000, 11000);
 
 	gpiod_set_value_cansleep(anx6345->gpiod_reset, 0);