Re: [PATCH] drm/drm_connector: add additional aspect ratio values

["Ville Syrjälä" <ville.syrjala-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Thu, Sep 05, 2019 at 02:59:53PM +0000, Lin, Wayne wrote:
> 
> 
> ________________________________
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Sent: Saturday, August 24, 2019 02:41
> To: Lin, Wayne <Wayne.Lin@amd.com>
> Cc: dri-devel@lists.freedesktop.org <dri-devel@lists.freedesktop.org>; amd-gfx@lists.freedesktop.org <amd-gfx@lists.freedesktop.org>; Li, Sun peng (Leo) <Sunpeng.Li@amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com>
> Subject: Re: [PATCH] drm/drm_connector: add additional aspect ratio values
> 
> On Thu, Aug 22, 2019 at 05:50:02PM -0400, Wayne Lin wrote:
> > For HDMI2.0 CTS item - HF1-35, it verifies if the source generates
> > video timing "64:27" video format correctly.
> >
> > eg: (vic-76) 1920x1080p@60Hz,24bpp
> >
> > This patch add on "64:27" and "256:135" to drm_aspect_ratio_enum_list.
> > Thereafter, one can specify the aspect ratio to "64:27" or "256:135"
> > after creating aspect ratio property.
> >
> > Change-Id: Ifc9df54e8e8f78e70960fcd737a3a57e49c81152
> > Signed-off-by: Wayne Lin <waynelin@amd.com>
> > ---
> >  drivers/gpu/drm/drm_connector.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > index 3a0cacb71235..c0629a01d08e 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -772,6 +772,8 @@ static const struct drm_prop_enum_list drm_aspect_ratio_enum_list[] = {
> >        { DRM_MODE_PICTURE_ASPECT_NONE, "Automatic" },
> >        { DRM_MODE_PICTURE_ASPECT_4_3, "4:3" },
> >        { DRM_MODE_PICTURE_ASPECT_16_9, "16:9" },
> > +     { DRM_MODE_PICTURE_ASPECT_64_27, "64:27" },
> > +     { DRM_MODE_PICTURE_ASPECT_256_135, "256:135" },
> 
> > Not 100% sure we want to expose these via the property because the
> > infoframe can't convey these independently from the VIC.
> 
> Agree with that it can't be independent from the VIC.
> When building up hdmi avi infoframe by using "drm_hdmi_avi_infoframe_from_display_mode" in drm_edid,
> it will refer to the VIC to set up the aspect ratio if the aspect ratio is not specified in mode.
> However, if the aspect ratio is specified to a value other than none, current logic of code will use the specified value.
> 
> The main reason of this patch is for capable indicating the exact VIC wanted.
> There are some modes defined in CTA-861 with same timing but different aspect ratio.
> eg: VIC 103 & VIC 93
> Without these new definitions, we cannot distinguish these different modes and might set a wrong VIC in AVI infoframe.

The mode flags already contain the aspect ratio information.
You just need the appropriate client cap to use them.

-- 
Ville Syrjälä
Intel
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