From 17b1f13ae0da5d48b82167b6354dd5d7a6dfe8d6 Mon Sep 17 00:00:00 2001
From: John Stultz <jstultz@google.com>
Date: Wed, 11 May 2022 01:26:12 +0000
Subject: drm/bridge: lt9611: Use both bits for HDMI sensing
Git-commit: 649eb3828fb22e829e222ebd83f4e11dc503a565
Patch-mainline: v6.0-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 jsc#PED-2849

In commit 19cf41b64e3b ("lontium-lt9611: check a different
register bit for HDMI sensing"), the bit flag used to detect
HDMI cable connect was switched from BIT(2) to BIT(0) to improve
compatibility with some monitors that didn't seem to set BIT(2).

However, with that change, I've seen occasional issues where the
detection failed, because BIT(2) was set, but not BIT(0).

Unfortunately, as I understand it, the bits and their function
was never clearly documented. So lets instead check both
(BIT(2) | BIT(0)) when checking the register.

Cc: Yongqin Liu <yongqin.liu@linaro.org>
Cc: Amit Pundir <amit.pundir@linaro.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vinod Koul <vkoul@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: kernel-team@android.com
Fixes: 19cf41b64e3b ("lontium-lt9611: check a different register bit for HDMI sensing")
Signed-off-by: John Stultz <jstultz@google.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220511012612.3297577-2-jstultz@google.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/bridge/lontium-lt9611.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
index 08a9b606c12d..88f2a4f43cfb 100644
--- a/drivers/gpu/drm/bridge/lontium-lt9611.c
+++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
@@ -584,7 +584,7 @@ static enum drm_connector_status __lt9611_detect(struct lt9611 *lt9611)
 	int connected = 0;
 
 	regmap_read(lt9611->regmap, 0x825e, &reg_val);
-	connected  = (reg_val & BIT(0));
+	connected  = (reg_val & (BIT(2) | BIT(0)));
 
 	lt9611->status = connected ?  connector_status_connected :
 				connector_status_disconnected;
-- 
2.38.1