[PATCH v3 3/5] drm/edid: Add support for quirks visible to DRM core and drivers

[Jani Nikula]

On Thu, 05 Jun 2025, Imre Deak <imre.deak at intel.com> wrote:
> Add support for EDID based quirks which can be queried outside of the
> EDID parser iteself by DRM core and drivers. There are at least two such
> quirks applicable to all drivers: the DPCD register access probe quirk
> and the 128b/132b DPRX Lane Count Conversion quirk (see 3.5.2.16.3 in
> the v2.1a DP Standard). The latter quirk applies to panels with specific
> EDID panel names, support for defining a quirk this way will be added as
> a follow-up.
>
> v2: Reset global_quirks in drm_reset_display_info().
> v3: (Jani)
> - Use one list for both the global and internal quirks.
> - Drop change for panel name specific quirks.
> - Add comment about the way quirks should be queried.
>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c  | 8 +++++++-
>  include/drm/drm_connector.h | 4 +++-
>  include/drm/drm_edid.h      | 5 +++++
>  3 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 857ae0c47a1c3..9cca1e6e4736c 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -68,7 +68,7 @@ static int oui(u8 first, u8 second, u8 third)
>  
>  enum drm_edid_internal_quirk {
>  	/* First detailed mode wrong, use largest 60Hz mode */
> -	EDID_QUIRK_PREFER_LARGE_60,
> +	EDID_QUIRK_PREFER_LARGE_60 = DRM_EDID_QUIRK_NUM,
>  	/* Reported 135MHz pixel clock is too high, needs adjustment */
>  	EDID_QUIRK_135_CLOCK_TOO_HIGH,
>  	/* Prefer the largest mode at 75 Hz */
> @@ -2959,6 +2959,12 @@ static bool drm_edid_has_internal_quirk(struct drm_connector *connector,
>  	return connector->display_info.quirks & BIT(quirk);
>  }
>  
> +bool drm_edid_has_quirk(struct drm_connector *connector, enum drm_edid_quirk quirk)

Nitpick, this could've been const.

Regardless,

Reviewed-by: Jani Nikula <jani.nikula at intel.com>



> +{
> +	return connector->display_info.quirks & BIT(quirk);
> +}
> +EXPORT_SYMBOL(drm_edid_has_quirk);
> +
>  #define MODE_SIZE(m) ((m)->hdisplay * (m)->vdisplay)
>  #define MODE_REFRESH_DIFF(c,t) (abs((c) - (t)))
>  
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 73903c3c842f3..137773dd138ea 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -843,7 +843,9 @@ struct drm_display_info {
>  	int vics_len;
>  
>  	/**
> -	 * @quirks: EDID based quirks. Internal to EDID parsing.
> +	 * @quirks: EDID based quirks. DRM core and drivers can query the
> +	 * @drm_edid_quirk quirks using drm_edid_has_quirk(), the rest of
> +	 * the quirks also tracked here are internal to EDID parsing.
>  	 */
>  	u32 quirks;
>  
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index b38409670868d..77fd42608e706 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -109,6 +109,10 @@ struct detailed_data_string {
>  #define DRM_EDID_CVT_FLAGS_STANDARD_BLANKING (1 << 3)
>  #define DRM_EDID_CVT_FLAGS_REDUCED_BLANKING  (1 << 4)
>  
> +enum drm_edid_quirk {
> +	DRM_EDID_QUIRK_NUM,
> +};
> +
>  struct detailed_data_monitor_range {
>  	u8 min_vfreq;
>  	u8 max_vfreq;
> @@ -476,5 +480,6 @@ void drm_edid_print_product_id(struct drm_printer *p,
>  u32 drm_edid_get_panel_id(const struct drm_edid *drm_edid);
>  bool drm_edid_match(const struct drm_edid *drm_edid,
>  		    const struct drm_edid_ident *ident);
> +bool drm_edid_has_quirk(struct drm_connector *connector, enum drm_edid_quirk quirk);
>  
>  #endif /* __DRM_EDID_H__ */

-- 
Jani Nikula, Intel