linux-kernel - Re: [PATCH v2] drm/bridge: sii902x: Fix HDMI detection with DRM_BRIDGE_ATTACH_NO

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Message-ID: <d14f940ed04e04df4a112588cdb6fa4df770b9fb@intel.com>
Date: Mon, 06 Oct 2025 18:13:30 +0300
From: Jani Nikula <jani.nikula@...el.com>
To: Devarsh Thakkar <devarsht@...com>, 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, dmitry.baryshkov@....qualcomm.com
Cc: tomi.valkeinen@...asonboard.com, praneeth@...com, vigneshr@...com,
 aradhya.bhatia@...ux.dev, s-jain1@...com, s-wang12@...com,
 r-donadkar@...com, h-shenoy@...com, devarsht@...com
Subject: Re: [PATCH v2] drm/bridge: sii902x: Fix HDMI detection with
 DRM_BRIDGE_ATTACH_NO_CONNECTOR

On Mon, 06 Oct 2025, Devarsh Thakkar <devarsht@...com> 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>
> ---
> V2: Use drm_edid_connector_update to detect HDMI as suggested
>
> Link to V1:
> https://lore.kernel.org/all/20251003143642.4072918-1-devarsht@ti.com/
> ---
>  drivers/gpu/drm/bridge/sii902x.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> index d537b1d036fb..d36466d73385 100644
> --- a/drivers/gpu/drm/bridge/sii902x.c
> +++ b/drivers/gpu/drm/bridge/sii902x.c
> @@ -296,6 +296,10 @@ static const struct drm_edid *sii902x_edid_read(struct sii902x *sii902x,
>  	mutex_lock(&sii902x->mutex);
>  
>  	drm_edid = drm_edid_read_ddc(connector, sii902x->i2cmux->adapter[0]);
> +	if (drm_edid) {
> +		drm_edid_connector_update(connector, drm_edid);

Mmmh, as a rule, you should do drm_edid_connector_update() even if it's
NULL to reset all the previous stuff.

BR,
Jani.

> +		sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
> +	}
>  
>  	mutex_unlock(&sii902x->mutex);
>  
> @@ -309,14 +313,11 @@ static int sii902x_get_modes(struct drm_connector *connector)
>  	int num = 0;
>  
>  	drm_edid = sii902x_edid_read(sii902x, connector);
> -	drm_edid_connector_update(connector, drm_edid);
>  	if (drm_edid) {
>  		num = drm_edid_connector_add_modes(connector);
>  		drm_edid_free(drm_edid);
>  	}
>  
> -	sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
> -
>  	return num;
>  }

-- 
Jani Nikula, Intel