Re: [PATCH 4/4] drm/edid: Prep for HDMI VIC aspect ratio (WIP)

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: "Lin, Wayne" <Wayne.Lin@amd.com>
Cc: "intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 4/4] drm/edid: Prep for HDMI VIC aspect ratio (WIP)
Date: Mon, 14 Oct 2019 17:41:57 +0300	[thread overview]
Message-ID: <20191014144157.GU1208@intel.com> (raw)
In-Reply-To: <DM6PR12MB4137CFEE415283752693EDC0FC900@DM6PR12MB4137.namprd12.prod.outlook.com>

On Mon, Oct 14, 2019 at 09:27:07AM +0000, Lin, Wayne wrote:
> 
> 
> > -----Original Message-----
> > From: Ville Syrjala <ville.syrjala@linux.intel.com>
> > Sent: Friday, October 4, 2019 10:19 PM
> > To: dri-devel@lists.freedesktop.org
> > Cc: intel-gfx@lists.freedesktop.org; Lin, Wayne <Wayne.Lin@amd.com>
> > Subject: [PATCH 4/4] drm/edid: Prep for HDMI VIC aspect ratio (WIP)
> > 
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > I think this should provide most of necessary logic for adding aspecr ratios to
> > the HDMI 4k modes.
> > 
> > Cc: Wayne Lin <waynelin@amd.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/drm_edid.c | 37 +++++++++++++++++++++++++++++++------
> >  1 file changed, 31 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index
> > c7f9f7ca75a2..c76814edc784 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -3210,6 +3210,11 @@ static enum hdmi_picture_aspect
> > drm_get_cea_aspect_ratio(const u8 video_code)
> >  	return edid_cea_modes[video_code].picture_aspect_ratio;
> >  }
> > 
> > +static enum hdmi_picture_aspect drm_get_hdmi_aspect_ratio(const u8
> > +video_code) {
> > +	return edid_4k_modes[video_code].picture_aspect_ratio;
> > +}
> > +
> 
> There are no picture_aspect_ratio attributes defined for modes in 
> edid_4k_modes[] now. Should add on those definitions.
> 
> >  /*
> >   * Calculate the alternate clock for HDMI modes (those from the HDMI
> > vendor
> >   * specific block).
> > @@ -3236,6 +3241,9 @@ static u8
> > drm_match_hdmi_mode_clock_tolerance(const struct drm_display_mode *to_
> >  	if (!to_match->clock)
> >  		return 0;
> > 
> > +	if (to_match->picture_aspect_ratio)
> > +		match_flags |= DRM_MODE_MATCH_ASPECT_RATIO;
> > +
> >  	for (vic = 1; vic < ARRAY_SIZE(edid_4k_modes); vic++) {
> >  		const struct drm_display_mode *hdmi_mode =
> > &edid_4k_modes[vic];
> >  		unsigned int clock1, clock2;
> > @@ -3271,6 +3279,9 @@ static u8 drm_match_hdmi_mode(const struct
> > drm_display_mode *to_match)
> >  	if (!to_match->clock)
> >  		return 0;
> > 
> > +	if (to_match->picture_aspect_ratio)
> > +		match_flags |= DRM_MODE_MATCH_ASPECT_RATIO;
> > +
> >  	for (vic = 1; vic < ARRAY_SIZE(edid_4k_modes); vic++) {
> >  		const struct drm_display_mode *hdmi_mode =
> > &edid_4k_modes[vic];
> >  		unsigned int clock1, clock2;
> 
> Current code in drm_match_hdmi_mdoe() & drm_match_hdmi_mode_clock_tolerance()
> use hdmi_mode_alternate_clock() to find alternate clocks.
> In hdmi_mode_alternate_clock(), it adds an exception for VIC 4 mode (4096x2160@24)
> due to there is no alternate clock defined for that mode in HDMI1.4b. But HDMI2.0 adds
> 23.98Hz for that mode. Maybe we should also revise that part.

I'm tempted to just remove that exception. I have a hard time imagining
it causing serious problems.

> 
> > @@ -5218,6 +5229,7 @@
> > drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe
> > *frame,
> >  					 const struct drm_display_mode *mode)  {
> >  	enum hdmi_picture_aspect picture_aspect;
> > +	u8 vic, hdmi_vic;
> >  	int err;
> > 
> >  	if (!frame || !mode)
> > @@ -5230,7 +5242,8 @@
> > drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe
> > *frame,
> >  	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
> >  		frame->pixel_repeat = 1;
> > 
> > -	frame->video_code = drm_mode_cea_vic(connector, mode);
> > +	vic = drm_mode_cea_vic(connector, mode);
> > +	hdmi_vic = drm_mode_hdmi_vic(connector, mode);
> > 
> >  	frame->picture_aspect = HDMI_PICTURE_ASPECT_NONE;
> > 
> > @@ -5244,11 +5257,15 @@
> > drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe
> > *frame,
> > 
> >  	/*
> >  	 * Populate picture aspect ratio from either
> > -	 * user input (if specified) or from the CEA mode list.
> > +	 * user input (if specified) or from the CEA/HDMI mode lists.
> >  	 */
> >  	picture_aspect = mode->picture_aspect_ratio;
> > -	if (picture_aspect == HDMI_PICTURE_ASPECT_NONE)
> > -		picture_aspect = drm_get_cea_aspect_ratio(frame->video_code);
> > +	if (picture_aspect == HDMI_PICTURE_ASPECT_NONE) {
> > +		if (vic)
> > +			picture_aspect = drm_get_cea_aspect_ratio(vic);
> > +		else if (hdmi_vic)
> > +			picture_aspect = drm_get_hdmi_aspect_ratio(hdmi_vic);
> > +	}
> > 
> >  	/*
> >  	 * The infoframe can't convey anything but none, 4:3 @@ -5256,12
> > +5273,20 @@ drm_hdmi_avi_infoframe_from_display_mode(struct
> > hdmi_avi_infoframe *frame,
> >  	 * we can only satisfy it by specifying the right VIC.
> >  	 */
> >  	if (picture_aspect > HDMI_PICTURE_ASPECT_16_9) {
> > -		if (picture_aspect !=
> > -		    drm_get_cea_aspect_ratio(frame->video_code))
> > +		if (vic) {
> > +			if (picture_aspect != drm_get_cea_aspect_ratio(vic))
> > +				return -EINVAL;
> > +		} else if (hdmi_vic) {
> > +			if (picture_aspect != drm_get_hdmi_aspect_ratio(hdmi_vic))
> > +				return -EINVAL;
> > +		} else {
> >  			return -EINVAL;
> > +		}
> > +
> >  		picture_aspect = HDMI_PICTURE_ASPECT_NONE;
> >  	}
> > 
> > +	frame->video_code = vic;
> >  	frame->picture_aspect = picture_aspect;
> >  	frame->active_aspect = HDMI_ACTIVE_ASPECT_PICTURE;
> >  	frame->scan_mode = HDMI_SCAN_MODE_UNDERSCAN;
> > --
> > 2.21.0
> 
> --
> Wayne Lin

-- 
Ville Syrjälä
Intel
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