[PATCH 2/2] drm/edid: Ignore "DFP 1.x" bit for EDID 1.2 and earlier

[Alex Deucher]

On Wed, May 29, 2019 at 7:02 AM Ville Syrjala
<ville.syrjala at linux.intel.com> wrote:
>
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> From VESA EDID implementation guide v1.0:
> "For EDID version 1 revision 2 or earlier data structures when offset 14h
>  bit 7 is set to one, the value of bits 6-0 are undefined, and therefore
>  cannot be interpreted to mean anything."
>
> And since EDID 1.4 redefines that bit let's consult it only for
> EDID 1.3.
>
> Cc: Mario Kleiner <mario.kleiner.de at gmail.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Series is:
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/drm_edid.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index dd601ed6a30e..c3296a72fff9 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4569,8 +4569,8 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
>          * tells us to assume 8 bpc color depth if the EDID doesn't have
>          * extensions which tell otherwise.
>          */
> -       if ((info->bpc == 0) && (edid->revision < 4) &&
> -           (edid->input & DRM_EDID_DIGITAL_DFP_1_X)) {
> +       if (info->bpc == 0 && edid->revision == 3 &&
> +           edid->input & DRM_EDID_DIGITAL_DFP_1_X) {
>                 info->bpc = 8;
>                 DRM_DEBUG("%s: Assigning DFP sink color depth as %d bpc.\n",
>                           connector->name, info->bpc);
> --
> 2.21.0
>
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