From 7a71ad83873975de63892a997aefaf14494e7e6d Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <pcc@google.com>
Date: Tue, 16 Nov 2021 18:07:24 -0800
Subject: lontium-lt9611: check a different register bit for HDMI sensing
Git-commit: 19cf41b64e3b150cf64fa01dec13f20dc86d95b2
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

It has been observed that with certain monitors such as the HP Z27n,
the register 0x825e reads a value of 0x79 when the HDMI cable is
connected and 0x78 when it is disconnected, i.e. bit 0 appears
to correspond to the HDMI connection status and bit 2 is never
set. Therefore, change the driver to check bit 0 instead of bit 2.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I7e76411127e1ce4988a3f6d0c8ba5f1c3d880c23
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211117020724.2647769-1-pcc@google.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/bridge/lontium-lt9611.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
index d2f45a0f79c8..dafb1b47c15f 100644
--- a/drivers/gpu/drm/bridge/lontium-lt9611.c
+++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
@@ -586,7 +586,7 @@ lt9611_connector_detect(struct drm_connector *connector, bool force)
 	int connected = 0;
 
 	regmap_read(lt9611->regmap, 0x825e, &reg_val);
-	connected  = (reg_val & BIT(2));
+	connected  = (reg_val & BIT(0));
 
 	lt9611->status = connected ?  connector_status_connected :
 				connector_status_disconnected;
@@ -892,7 +892,7 @@ static enum drm_connector_status lt9611_bridge_detect(struct drm_bridge *bridge)
 	int connected;
 
 	regmap_read(lt9611->regmap, 0x825e, &reg_val);
-	connected  = reg_val & BIT(2);
+	connected  = reg_val & BIT(0);
 
 	lt9611->status = connected ?  connector_status_connected :
 				connector_status_disconnected;
-- 
2.38.1