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From: Kuogee Hsieh <khsieh@codeaurora.org>
To: robdclark@gmail.com, sean@poorly.run, swboyd@chromium.org
Cc: Kuogee Hsieh <khsieh@codeaurora.org>,
	abhinavk@codeaurora.org, aravindh@codeaurora.org,
	airlied@linux.ie, daniel@ffwll.ch, linux-arm-msm@vger.kernel.org,
	dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 3/4] drm/msm/dp: check main link status before start aux read
Date: Wed, 21 Apr 2021 16:37:37 -0700	[thread overview]
Message-ID: <1619048258-8717-4-git-send-email-khsieh@codeaurora.org> (raw)
In-Reply-To: <1619048258-8717-1-git-send-email-khsieh@codeaurora.org>

Maybe when the cable is disconnected the DP phy should be shutdown and
some bit in the phy could effectively "cut off" the aux channel and then
NAKs would start coming through here in the DP controller I/O register
space. This patch have DP aux channel read/write to return NAK immediately
if DP controller connection status is in unplugged state.

Changes in V4:
-- split this patch as stand alone patch

Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_aux.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c
index 7c22bfe..fae3806 100644
--- a/drivers/gpu/drm/msm/dp/dp_aux.c
+++ b/drivers/gpu/drm/msm/dp/dp_aux.c
@@ -343,6 +343,11 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
 
 	mutex_lock(&aux->mutex);
 
+	if (!dp_catalog_link_is_connected(aux->catalog)) {
+		ret = -ETIMEDOUT;
+		goto unlock_exit;
+	}
+
 	aux->native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);
 
 	/* Ignore address only message */
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project


  parent reply	other threads:[~2021-04-21 23:38 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-21 23:37 [PATCH v4 0/4] check sink_count before update is_connected status Kuogee Hsieh
2021-04-21 23:37 ` [PATCH v4 1/4] drm/msm/dp: " Kuogee Hsieh
2021-05-04  4:30   ` Stephen Boyd
2021-04-21 23:37 ` [PATCH v4 2/4] drm/msm/dp: initialize audio_comp when audio starts Kuogee Hsieh
2021-05-04  4:32   ` Stephen Boyd
2021-04-21 23:37 ` Kuogee Hsieh [this message]
2021-05-04  4:42   ` [PATCH v4 3/4] drm/msm/dp: check main link status before start aux read Stephen Boyd
2021-04-21 23:37 ` [PATCH v4 4/4] drm/msm/dp: dp_link_parse_sink_count() return immediately if aux read failed Kuogee Hsieh
2021-05-04  4:35   ` Stephen Boyd
2021-11-25  7:32     ` Dmitry Baryshkov
2021-12-01 20:48       ` khsieh
2021-05-07  0:23 ` [PATCH v4 0/4] check sink_count before update is_connected status Rob Clark

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