Re: [PATCH v2] drm/gma500: replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi

[Thomas Zimmermann]

Hi

Am 12.09.24 um 10:56 schrieb Jani Nikula:
> On Thu, 12 Sep 2024, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
> > On Thu, 12 Sep 2024, Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
> > > Hi
> > >
> > > Am 11.09.24 um 20:06 schrieb Tejas Vipin:
> > > > Replace drm_detect_hdmi_monitor() with drm_display_info.is_hdmi since
> > > > monitor HDMI information is available after EDID is parsed. Additionally
> > > > rewrite the code the code to have fewer indentation levels.
> > > The problem is that the entire logic is outdated. The content
> > > of cdv_hdmi_detect() should go into cdv_hdmi_get_modes(), the detect_ctx
> > > callback should be set to drm_connector_helper_detect_from_ddc() and
> > > cdv_hdmi_detect() should be deleted. The result is that ->detect_ctx
> > > will detect the presence of a display and ->get_modes will update EDID
> > > and other properties.
> > I guess I didn't get the memo on this one.
> >
> > What's the problem with reading the EDID at detect? The subsequent
> > drm_edid_connector_add_modes() called from .get_modes() does not need to
> > read the EDID again.
> Moreover, in this case .detect() only detects digital displays as
> reported by EDID. If you postpone that to .get_modes(), the probe helper
> will still report connected, and invent non-EDID fallback modes. The
> behaviour changes.

The change in behavior is intentional, because the current test seems 
arbitrary. Does the driver not work with analog outputs?

Best regards
Thomas

> > I think it should be fine to do incremental refactors like the patch at
> > hand (modulo some issues I mention below).
> Another issue in the patch is that it should also change .get_modes() to
> not read the EDID again, but just call drm_edid_connector_add_modes().
>
> BR,
> Jani.
>
> > BR,
> > Jani.
> >
> >
> > > Do you have  a device for testing such a change?
> > >
> > > Best regards
> > > Thomas
> > >
> > > > Signed-off-by: Tejas Vipin <tejasvipin76@xxxxxxxxx>
> > > > ---
> > > > Changes in v2:
> > > >       - Use drm_edid instead of edid
> > > >
> > > > Link to v1: https://lore.kernel.org/all/20240910051856.700210-1-tejasvipin76@xxxxxxxxx/
> > > > ---
> > > >    drivers/gpu/drm/gma500/cdv_intel_hdmi.c | 24 +++++++++++++-----------
> > > >    1 file changed, 13 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/gma500/cdv_intel_hdmi.c b/drivers/gpu/drm/gma500/cdv_intel_hdmi.c
> > > > index 2d95e0471291..701f8bbd5f2b 100644
> > > > --- a/drivers/gpu/drm/gma500/cdv_intel_hdmi.c
> > > > +++ b/drivers/gpu/drm/gma500/cdv_intel_hdmi.c
> > > > @@ -128,23 +128,25 @@ static enum drm_connector_status cdv_hdmi_detect(
> > > >    {
> > > >    	struct gma_encoder *gma_encoder = gma_attached_encoder(connector);
> > > >    	struct mid_intel_hdmi_priv *hdmi_priv = gma_encoder->dev_priv;
> > > > -	struct edid *edid = NULL;
> > > > +	const struct drm_edid *drm_edid;
> > > > +	int ret;
> > > >    	enum drm_connector_status status = connector_status_disconnected;
> > > >    
> > > > -	edid = drm_get_edid(connector, connector->ddc);
> > > > +	drm_edid = drm_edid_read_ddc(connector, connector->ddc);
> > Just drm_edid_read() is enough when you're using connector->ddc.
> >
> > > > +	ret = drm_edid_connector_update(connector, drm_edid);
> > > >    
> > > >    	hdmi_priv->has_hdmi_sink = false;
> > > >    	hdmi_priv->has_hdmi_audio = false;
> > > > -	if (edid) {
> > > > -		if (edid->input & DRM_EDID_INPUT_DIGITAL) {
> > > > -			status = connector_status_connected;
> > > > -			hdmi_priv->has_hdmi_sink =
> > > > -						drm_detect_hdmi_monitor(edid);
> > > > -			hdmi_priv->has_hdmi_audio =
> > > > -						drm_detect_monitor_audio(edid);
> > > > -		}
> > > > -		kfree(edid);
> > > > +	if (ret)
> > This error path leaks the EDID.
> >
> > > > +		return status;
> > > > +
> > > > +	if (drm_edid_is_digital(drm_edid)) {
> > > > +		status = connector_status_connected;
> > > > +		hdmi_priv->has_hdmi_sink = connector->display_info.is_hdmi;
> > > > +		hdmi_priv->has_hdmi_audio = connector->display_info.has_audio;
> > > >    	}
> > > > +	drm_edid_free(drm_edid);
> > > > +
> > > >    	return status;
> > > >    }
> > > >    

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)