public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: John Stultz <jstultz@google.com>
To: linux-kernel@vger.kernel.org
Cc: John Stultz <jstultz@google.com>,
	Yongqin Liu <yongqin.liu@linaro.org>,
	Amit Pundir <amit.pundir@linaro.org>,
	Peter Collingbourne <pcc@google.com>,
	Vinod Koul <vkoul@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Robert Foss <robert.foss@linaro.org>,
	kernel-team@android.com
Subject: [PATCH 2/2] drm/bridge: lt9611: Use both bits for HDMI sensing
Date: Wed, 11 May 2022 01:26:12 +0000	[thread overview]
Message-ID: <20220511012612.3297577-2-jstultz@google.com> (raw)
In-Reply-To: <20220511012612.3297577-1-jstultz@google.com>

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>
---
 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 bf66af668f61..a11604a56e08 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;
-- 
2.36.0.512.ge40c2bad7a-goog


  reply	other threads:[~2022-05-11  1:28 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-11  1:26 [PATCH 1/2] drm/bridge: lt9611: Consolidate detection logic John Stultz
2022-05-11  1:26 ` John Stultz [this message]
2022-05-23 10:18   ` [PATCH 2/2] drm/bridge: lt9611: Use both bits for HDMI sensing Robert Foss

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220511012612.3297577-2-jstultz@google.com \
    --to=jstultz@google.com \
    --cc=amit.pundir@linaro.org \
    --cc=bjorn.andersson@linaro.org \
    --cc=kernel-team@android.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pcc@google.com \
    --cc=robert.foss@linaro.org \
    --cc=vkoul@kernel.org \
    --cc=yongqin.liu@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox