On Tue, Feb 22, 2022 at 02:38:17PM +0800, Lee Shawn C wrote:
> Try to find and parse more CEA ext blocks if edid->extensions
> is greater than one.
> 
> Cc: Jani Nikula <jani.nik...@linux.intel.com>
> Cc: Ville Syrjala <ville.syrj...@linux.intel.com>
> Cc: Ankit Nautiyal <ankit.k.nauti...@intel.com>
> Signed-off-by: Lee Shawn C <shawn.c....@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 75 +++++++++++++++++++++++---------------
>  1 file changed, 45 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 12893e7be89b..3d5dbbeca7f9 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4313,43 +4313,58 @@ add_cea_modes(struct drm_connector *connector, struct 
> edid *edid)
>       const u8 *cea = drm_find_cea_extension(edid);
>       const u8 *db, *hdmi = NULL, *video = NULL;
>       u8 dbl, hdmi_len, video_len = 0;
> -     int modes = 0;
> +     int modes = 0, j;
>  
> -     if (cea && cea_revision(cea) >= 3) {
> -             int i, start, end;
> +     if (!cea)
> +             return 0;
>  
> -             if (cea_db_offsets(cea, &start, &end))
> -                     return 0;
> +     for (j = (cea - (u8 *)edid) / EDID_LENGTH; j <= edid->extensions;) {

That looks rather illegible. I think we want a
drm_find_cea_extension(const struct edid *edid, int *ext_index)
and then just loop until it stops giving us stuff.

There are also several other callers of drm_find_cea_extension().
Why don't they require the same treatment?

> +             if (cea && cea_revision(cea) >= 3) {
> +                     int i, start, end;
>  
> -             for_each_cea_db(cea, i, start, end) {
> -                     db = &cea[i];
> -                     dbl = cea_db_payload_len(db);
> +                     if (cea_db_offsets(cea, &start, &end))
> +                             continue;
>  
> -                     if (cea_db_tag(db) == VIDEO_BLOCK) {
> -                             video = db + 1;
> -                             video_len = dbl;
> -                             modes += do_cea_modes(connector, video, dbl);
> -                     } else if (cea_db_is_hdmi_vsdb(db)) {
> -                             hdmi = db;
> -                             hdmi_len = dbl;
> -                     } else if (cea_db_is_y420vdb(db)) {
> -                             const u8 *vdb420 = &db[2];
> -
> -                             /* Add 4:2:0(only) modes present in EDID */
> -                             modes += do_y420vdb_modes(connector,
> -                                                       vdb420,
> -                                                       dbl - 1);
> +                     for_each_cea_db(cea, i, start, end) {
> +                             db = &cea[i];
> +                             dbl = cea_db_payload_len(db);
> +
> +                             if (cea_db_tag(db) == VIDEO_BLOCK) {
> +                                     video = db + 1;
> +                                     video_len = dbl;
> +                                     modes += do_cea_modes(connector, video, 
> dbl);
> +                             } else if (cea_db_is_hdmi_vsdb(db)) {
> +                                     hdmi = db;
> +                                     hdmi_len = dbl;
> +                             } else if (cea_db_is_y420vdb(db)) {
> +                                     const u8 *vdb420 = &db[2];
> +
> +                                     /* Add 4:2:0(only) modes present in 
> EDID */
> +                                     modes += do_y420vdb_modes(connector,
> +                                                               vdb420,
> +                                                               dbl - 1);
> +                             }
>                       }
>               }
> -     }
>  
> -     /*
> -      * We parse the HDMI VSDB after having added the cea modes as we will
> -      * be patching their flags when the sink supports stereo 3D.
> -      */
> -     if (hdmi)
> -             modes += do_hdmi_vsdb_modes(connector, hdmi, hdmi_len, video,
> -                                         video_len);
> +             /*
> +              * We parse the HDMI VSDB after having added the cea modes as 
> we will
> +              * be patching their flags when the sink supports stereo 3D.
> +              */
> +             if (hdmi) {
> +                     modes += do_hdmi_vsdb_modes(connector, hdmi, hdmi_len, 
> video,
> +                                                 video_len);
> +                     hdmi  = NULL;
> +                     video = NULL;
> +                     hdmi_len = 0;
> +                     video_len = 0;
> +             }
> +
> +             /* move to next CEA extension block */
> +             cea = drm_find_edid_extension(edid, CEA_EXT, &j);
> +             if (!cea)
> +                     break;
> +     }
>  
>       return modes;
>  }
> -- 
> 2.17.1

-- 
Ville Syrjälä
Intel

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