linux-kernel - Re: [PATCH] drm/bridge: sii902x: Fix HDMI detection with DRM_BRIDGE_ATTACH_NO

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Message-ID: <gc7prlpfdb4zgqtxz5fog2mi4x6vefwcrnuw53i6xbd3vguf3h@gtb3bdy7zogu>
Date: Sat, 4 Oct 2025 12:53:07 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Devarsh Thakkar <devarsht@...com>
Cc: andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org,
        airlied@...il.com, maarten.lankhorst@...ux.intel.com,
        mripard@...nel.org, tzimmermann@...e.de,
        dri-devel@...ts.freedesktop.org, simona@...ll.ch,
        linux-kernel@...r.kernel.org, tomi.valkeinen@...asonboard.com,
        jani.nikula@...el.com, praneeth@...com, vigneshr@...com,
        aradhya.bhatia@...ux.dev, s-jain1@...com, s-wang12@...com,
        r-donadkar@...com, h-shenoy@...com
Subject: Re: [PATCH] drm/bridge: sii902x: Fix HDMI detection with
 DRM_BRIDGE_ATTACH_NO_CONNECTOR

On Fri, Oct 03, 2025 at 08:06:42PM +0530, Devarsh Thakkar wrote:
> The SII902x HDMI bridge driver wasn't working properly with drivers that
> use the newer bridge connector architecture with the
> DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, like TIDSS.  This caused HDMI audio to
> fail since the driver wasn't properly setting the sink_is_hdmi flag when
> the bridge was attached without a connector since .get_modes() is never
> called in this case. Fix it by setting sink_is_hdmi flag when reading
> the EDID block itself.
> 
> Fixes: 3de47e1309c2 ("drm/bridge: sii902x: use display info is_hdmi")
> Signed-off-by: Devarsh Thakkar <devarsht@...com>
> ---
>  drivers/gpu/drm/bridge/sii902x.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> index d537b1d036fb..3d169b9fac70 100644
> --- a/drivers/gpu/drm/bridge/sii902x.c
> +++ b/drivers/gpu/drm/bridge/sii902x.c
> @@ -292,10 +292,16 @@ static const struct drm_edid *sii902x_edid_read(struct sii902x *sii902x,
>  						struct drm_connector *connector)
>  {
>  	const struct drm_edid *drm_edid;
> +	const struct edid *edid;
>  
>  	mutex_lock(&sii902x->mutex);
>  
>  	drm_edid = drm_edid_read_ddc(connector, sii902x->i2cmux->adapter[0]);
> +	if (drm_edid) {
> +		edid = drm_edid_raw(drm_edid);
> +		if (edid && drm_detect_hdmi_monitor(edid))
> +			sii902x->sink_is_hdmi = true;

Just call drm_edid_connector_update() here. The drm_edid_raw() has a
very nice comment:

 * This is for transition only. Avoid using this like the plague.


And we really need to convert the bridge to the HDMI helpers.

> +	}
>  
>  	mutex_unlock(&sii902x->mutex);
>  
> @@ -315,8 +321,6 @@ static int sii902x_get_modes(struct drm_connector *connector)
>  		drm_edid_free(drm_edid);
>  	}
>  
> -	sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
> -
>  	return num;
>  }
>  
> -- 
> 2.39.1
> 

-- 
With best wishes
Dmitry