[PATCH v4] drm/edid: ignore the CEA modes not defined in CEA-861-D

[Tseng, William]

For EDID, please refer to the attachment on the link.
https://gitlab.freedesktop.org/drm/intel/-/issues/6153#note_1558419


Regards
William

-----Original Message-----
From: Jani Nikula <jani.nikula at linux.intel.com> 
Sent: Tuesday, September 20, 2022 2:49 PM
To: Tseng, William <william.tseng at intel.com>; dri-devel at lists.freedesktop.org
Cc: Tseng, William <william.tseng at intel.com>; Ville Syrjälä <ville.syrjala at linux.intel.com>; Wayne Lin <waynelin at amd.com>; Lee, Shawn C <shawn.c.lee at intel.com>
Subject: Re: [PATCH v4] drm/edid: ignore the CEA modes not defined in CEA-861-D

On Tue, 20 Sep 2022, William Tseng <william.tseng at intel.com> wrote:
> This is a workaround for HDMI 1.4 sink which has a CEA mode with 
> higher vic than what is defined in CEA-861-D.
>
> As an example, a HDMI 1.4 sink has the video format 2560x1080p to be 
> displayed and the video format is indicated by both SVD (with vic 90 
> and picture aspect ratio 64:27) and DTD.  When connecting to such 
> sink, source can't output the video format in SVD because an error is 
> returned by drm_hdmi_avi_infoframe_from_display_mode(), which can't 
> fill the infoframe with picture aspect ratio 64:27 and the vic, which 
> is originally 90 and is changed to 0 by drm_mode_cea_vic().
>
> To work around it, do not set the vic 0 so the corresponding mode may 
> be accepted in drm_hdmi_avi_infoframe_from_display_mode() and be dispalyed.
>
> v1: initial version.
> v2: change the logic in drm_hdmi_avi_infoframe_from_display_mode().
> v3: fix typo.
> v4: add revision history.
>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Wayne Lin <waynelin at amd.com>
> Cc: Lee Shawn C <shawn.c.lee at intel.com>
> Signed-off-by: William Tseng <william.tseng at intel.com>

Please attach the offending EDID to the bug [1]. I won't ack this before we see the EDID in question.


BR,
Jani.


[1] https://gitlab.freedesktop.org/drm/intel/-/issues/6153

> ---
>  drivers/gpu/drm/drm_edid.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c 
> index eaa819381281..3c6a4e09b2d6 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -6640,7 +6640,8 @@ static u8 drm_mode_hdmi_vic(const struct 
> drm_connector *connector,  }
>  
>  static u8 drm_mode_cea_vic(const struct drm_connector *connector,
> -			   const struct drm_display_mode *mode)
> +			   const struct drm_display_mode *mode,
> +			   bool is_hdmi2_sink)
>  {
>  	u8 vic;
>  
> @@ -6660,7 +6661,7 @@ static u8 drm_mode_cea_vic(const struct drm_connector *connector,
>  	 * HDMI 2.0 VIC range: 1 <= VIC <= 107 (CEA-861-F). So we
>  	 * have to make sure we dont break HDMI 1.4 sinks.
>  	 */
> -	if (!is_hdmi2_sink(connector) && vic > 64)
> +	if (!is_hdmi2_sink && vic > 64)
>  		return 0;
>  
>  	return vic;
> @@ -6691,7 +6692,7 @@ drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe *frame,
>  	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
>  		frame->pixel_repeat = 1;
>  
> -	vic = drm_mode_cea_vic(connector, mode);
> +	vic = drm_mode_cea_vic(connector, mode, true);
>  	hdmi_vic = drm_mode_hdmi_vic(connector, mode);
>  
>  	frame->picture_aspect = HDMI_PICTURE_ASPECT_NONE; @@ -6735,7 +6736,8 
> @@ drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe *frame,
>  		picture_aspect = HDMI_PICTURE_ASPECT_NONE;
>  	}
>  
> -	frame->video_code = vic;
> +	frame->video_code = drm_mode_cea_vic(connector, mode,
> +						is_hdmi2_sink(connector));
>  	frame->picture_aspect = picture_aspect;
>  	frame->active_aspect = HDMI_ACTIVE_ASPECT_PICTURE;
>  	frame->scan_mode = HDMI_SCAN_MODE_UNDERSCAN;

--
Jani Nikula, Intel Open Source Graphics Center