Re: [PATCH v3] drm/bridge: sii902x: Fix HDMI detection with DRM_BRIDGE_ATTACH_NO_CONNECTOR

[Devarsh Thakkar]

Hi Dmitry,

Thanks for the quick reviews.

On 09/10/25 01:48, Dmitry Baryshkov wrote:
> On Tue, Oct 07, 2025 at 04:53:09PM +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@xxxxxx>
> > ---
> > V3: Use drm_edid_connector_update without edid NULL check
> > V2: Use drm_edid_connector_update to detect HDMI
> >
> > Link to V2:
> > https://lore.kernel.org/all/20251006150714.3144368-1-devarsht@xxxxxx/
> > Link to V1:
> > https://lore.kernel.org/all/20251003143642.4072918-1-devarsht@xxxxxx/
> >
> >   drivers/gpu/drm/bridge/sii902x.c | 5 ++---
> >   1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> > index d537b1d036fb..bb613d4c281f 100644
> > --- a/drivers/gpu/drm/bridge/sii902x.c
> > +++ b/drivers/gpu/drm/bridge/sii902x.c
> > @@ -296,6 +296,8 @@ 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]);
> > +	drm_edid_connector_update(connector, drm_edid);
> > +	sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
> >   
> >   	mutex_unlock(&sii902x->mutex);
> >   
> > @@ -309,14 +311,11 @@ 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);
> >   	}
>
> The EDID read / free can also be dropped, they don't serve any purpose
> now.

Sorry I did not understand this clearly.
I have already removed drm_edid_connector_update from sii902x_get_modes 
since now it is taken care inside sii902x_edid_read itself which is also 
called by .get_modes (sii902x_get_modes).

We still need to read edid inside sii902x_get_modes as for the legacy 
driver scenario which don't use DRM_BRIDGE_ATTACH_NO_CONNECTOR as in 
those cases .get_modes will get called but bridge function .edid_read 
won't be called. Also as the caller is supposed to free the edid 
allocated so I have preserved drm_edid_free call in .get_modes as 
drm_edid_connector_add_modes is allocating a new drm_edid pointer already.

Kindly let me know if there is a misunderstanding here.

Regards
Devarsh

> >   
> > -	sii902x->sink_is_hdmi = connector->display_info.is_hdmi;
> > -
> >   	return num;
> >   }
> >   
> > --
> > 2.39.1