[Intel-gfx] [PATCH] drm/edid: Reset more of the display info

[Ville Syrjälä]

On Tue, Apr 24, 2018 at 04:18:37PM +0200, Daniel Vetter wrote:
> On Tue, Apr 24, 2018 at 04:02:50PM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > We're currently failing to reset everything in display_info.hdmi
> > which will potentially cause us to use stale information when
> > swapping monitors. Eg. if the user replaces a HDMI 2.0 monitor
> > with a HDMI 1.x monitor we will continue to think that the monitor
> > supports scrambling. That will lead to a black screen since the
> > HDMI 1.x monitor won't understand the scrambled signal.
> > 
> > Fix the problem by clearing display_info.hdmi fully. And while at
> > eliminate some duplicated code by calling drm_reset_display_info()
> > in drm_add_display_info().
> > 
> > Cc: Antony Chen <antonychen at qnap.com>
> > Cc: Shashank Sharma <shashank.sharma at intel.com>
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105655
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/drm_edid.c | 11 +++--------
> >  1 file changed, 3 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 134069f36482..39f1db4acda4 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -4451,6 +4451,7 @@ drm_reset_display_info(struct drm_connector *connector)
> >  	info->max_tmds_clock = 0;
> >  	info->dvi_dual = false;
> >  	info->has_hdmi_infoframe = false;
> > +	memset(&info->hdmi, 0, sizeof(info->hdmi));
> >  
> >  	info->non_desktop = 0;
> >  }
> > @@ -4462,17 +4463,11 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
> >  
> >  	u32 quirks = edid_get_quirks(edid);
> >  
> > +	drm_reset_display_info(connector);
> > +
> 
> Strictly speaking this is a separate bugfix, for the case where you
> immediately go from one output to a different one. Keith already fixed the
> case where at least somewhere in between you go to the disconnected state
> in:
> 
> commit 170178fe99dd212bf25e70c89bc4b6e195564ffc
> Author: Keith Packard <keithp at keithp.com>
> Date:   Wed Dec 13 00:44:26 2017 -0800
> 
>     drm: Update edid-derived drm_display_info fields at edid property set [v2]
> 
> With the above explained in the commit message:

The drm_reset_display_info() call is just the "deduplicate the code"
part. The memset() is the bugfix, and applies in all cases.

> 
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> >  	info->width_mm = edid->width_cm * 10;
> >  	info->height_mm = edid->height_cm * 10;
> >  
> > -	/* driver figures it out in this case */
> > -	info->bpc = 0;
> > -	info->color_formats = 0;
> > -	info->cea_rev = 0;
> > -	info->max_tmds_clock = 0;
> > -	info->dvi_dual = false;
> > -	info->has_hdmi_infoframe = false;
> > -
> >  	info->non_desktop = !!(quirks & EDID_QUIRK_NON_DESKTOP);
> >  
> >  	DRM_DEBUG_KMS("non_desktop set to %d\n", info->non_desktop);
> > -- 
> > 2.16.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel