On Tue, 31 May 2022, William Tseng <william.tseng@xxxxxxxxx> 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
> pictuure 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 pictuure 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, this patch ignores such CEA modes in do_cea_modes() so
> the modes won't be processed in drm_hdmi_avi_infoframe_from_display_mode().
> And only the video format in DTD can be dispalyed.
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Wayne Lin <waynelin@xxxxxxx>
> Cc: Lee Shawn C <shawn.c.lee@xxxxxxxxx>
> Signed-off-by: William Tseng <william.tseng@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_edid.c | 39 +++++++++++++++++++++++++-------------
> 1 file changed, 26 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index bc43e1b32092..a93f68878bfd 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3982,6 +3982,19 @@ drm_display_mode_from_cea_vic(struct drm_device *dev,
> }
> EXPORT_SYMBOL(drm_display_mode_from_cea_vic);
>
> +static bool is_hdmi2_sink(const struct drm_connector *connector)
> +{
> + /*
> + * FIXME: sil-sii8620 doesn't have a connector around when
> + * we need one, so we have to be prepared for a NULL connector.
> + */
> + if (!connector)
> + return true;
> +
> + return connector->display_info.hdmi.scdc.supported ||
> + connector->display_info.color_formats & DRM_COLOR_FORMAT_YCBCR420;
> +}
> +
> static int
> do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
> {
> @@ -3993,6 +4006,19 @@ do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
>
> mode = drm_display_mode_from_vic_index(connector, db, len, i);
> if (mode) {
> + u8 vic = svd_to_vic(db[i]);
> +
> + if (!drm_valid_cea_vic(vic))
> + continue;
drm_display_mode_from_vic_index() returns NULL in this case.
> +
> + /*
> + * HDMI 1.4 VIC range: 1 <= VIC <= 64 (CEA-861-D) but
> + * 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)
> + continue;
I'll need to double check if this is the right thing to do... but I
guess the question becomes if this shouldn't be within
drm_display_mode_from_vic_index().
Duplicating the condition from drm_mode_cea_vic() is probably not a good
idea.
The continues in both above branches leak the mode.
BR,
Jani.
> +
> /*
> * YCBCR420 capability block contains a bitmap which
> * gives the index of CEA modes from CEA VDB, which
> @@ -5846,19 +5872,6 @@ void drm_set_preferred_mode(struct drm_connector *connector,
> }
> EXPORT_SYMBOL(drm_set_preferred_mode);
>
> -static bool is_hdmi2_sink(const struct drm_connector *connector)
> -{
> - /*
> - * FIXME: sil-sii8620 doesn't have a connector around when
> - * we need one, so we have to be prepared for a NULL connector.
> - */
> - if (!connector)
> - return true;
> -
> - return connector->display_info.hdmi.scdc.supported ||
> - connector->display_info.color_formats & DRM_COLOR_FORMAT_YCBCR420;
> -}
> -
> static u8 drm_mode_hdmi_vic(const struct drm_connector *connector,
> const struct drm_display_mode *mode)
> {
--
Jani Nikula, Intel Open Source Graphics Center
