linux-kernel - [PATCH] drm/bridge: adv7533: Reset DSI receiver logic

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Message-ID: <20241113-adv7533-dsi-reset-v1-1-6c1069e35fd3@axis.com>
Date: Wed, 13 Nov 2024 08:40:15 +0100
From: Stefan Ekenberg <stefan.ekenberg@...s.com>
To: Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong
	<neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, Laurent Pinchart
	<Laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, "Jernej
 Skrabec" <jernej.skrabec@...il.com>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
CC: <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
	<kernel@...s.com>, Stefan Ekenberg <stefan.ekenberg@...s.com>
Subject: [PATCH] drm/bridge: adv7533: Reset DSI receiver logic

Reset DSI receiver logic during power on. The need for this change was
discovered when investigating issue with ADV7535. The symptom of the
problem was that ADV7535 continuously outputs a black image. This
happened for about 10% of the times that ADV7535 was powered on. The
rest of the times the image was as expected.

The solution in this patch (placement of reset and sleep time of 200ms)
is implemented as outlined by the Analog Devices support team.

Signed-off-by: Stefan Ekenberg <stefan.ekenberg@...s.com>
---
 drivers/gpu/drm/bridge/adv7511/adv7533.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
index 4481489aaf5ebf164313c86cbf3447d2d7914ab9..93085c2b872ed98f4ee394236dc66c568c0e5ccf 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
@@ -67,6 +67,15 @@ void adv7533_dsi_power_on(struct adv7511 *adv)
 {
 	struct mipi_dsi_device *dsi = adv->dsi;
 
+	/*
+	 * Reset DSI receiver block logic to avoid ADV7535 startup problem.
+	 * Without this reset it sometimes continuously fails to receive
+	 * incoming DSI packets and outputs black image.
+	 */
+	regmap_write(adv->regmap_cec, 0x26, 0x18);
+	msleep(200);
+	regmap_write(adv->regmap_cec, 0x26, 0x38);
+
 	if (adv->use_timing_gen)
 		adv7511_dsi_config_timing_gen(adv);
 

---
base-commit: 59b723cd2adbac2a34fc8e12c74ae26ae45bf230
change-id: 20241108-adv7533-dsi-reset-488c6fbb5e42

Best regards,
-- 
Stefan Ekenberg <stefan.ekenberg@...s.com>