Re: [PATCH 5/5] drm/msm/dp: mark the SST connector disconnected when MST is enabled

From: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
To: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <rfoss@kernel.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Luca Ceresoli <luca.ceresoli@bootlin.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Rob Clark <robin.clark@oss.qualcomm.com>,
	Dmitry Baryshkov <lumag@kernel.org>,
	Abhinav Kumar <abhinav.kumar@linux.dev>,
	Jessica Zhang <jesszhan0024@gmail.com>,
	Sean Paul <sean@poorly.run>,
	Marijn Suijten <marijn.suijten@somainline.org>,
	Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konradybcio@kernel.org>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org
Subject: Re: [PATCH 5/5] drm/msm/dp: mark the SST connector disconnected when MST is enabled
Date: Sun, 12 Jul 2026 13:56:58 +0300	[thread overview]
Message-ID: <sijdmdhcbxyg23gh6c62hspruvbnyqbdrtv2er3bh6n6ftolsp@b6o4khv6dofc> (raw)
In-Reply-To: <20260629-msm-dp-msttypec-v1-5-646a10256233@oss.qualcomm.com>

On Mon, Jun 29, 2026 at 10:48:07PM +0800, Yongxing Mou wrote:
> When MST becomes active, the initial HPD plug notification updates the
> SST connector state to connected.
> 
> However, the subsequent SST connector detect path reports disconnected
> while MST is enabled. This connected -> disconnected transition is then
> observed by the polling logic and may result in an unnecessary hotplug
> event.
> 
> Set the SST connector state to disconnected immediately after MST is
> initialized so that the detect path does not introduce a transient
> state change.
> 
> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
> ---
>  drivers/gpu/drm/msm/dp/dp_display.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 4ee391cc7165..f8ca60d6d714 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -352,8 +352,10 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
>  	if (dp->max_stream > 1 && drm_dp_read_mst_cap(dp->aux, dp->panel->dpcd))
>  		msm_dp_display_mst_init(dp);
>  
> -	if (dp->msm_dp_display.mst_active)
> +	if (dp->msm_dp_display.mst_active) {
> +		connector->status = connector_status_disconnected;
>  		msm_dp_mst_display_set_mgr_state(&dp->msm_dp_display, true);

This should be a part of the MST series.

> +	}
>  
>  	msm_dp_link_reset_phy_params_vx_px(dp->link);
>  
> 
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry

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