Re: [PATCH 06/20] drm: add helper to validate YCBCR420 modes

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Jul 10, 2017 at 04:48:34PM +0530, Shashank Sharma wrote:
> YCBCR420 modes are supported only on HDMI 2.0 capable sources.
> This patch adds:
> - A drm helper to validate YCBCR420-only mode on a particular
>   connector. This function will help pruning the YCBCR420-only
>   modes from the connector's modelist.
> - A bool variable (ycbcr_420_allowed) in the drm connector structure.
>   While handling the EDID from HDMI 2.0 sinks, its important to know
>   if the source is capable of handling YCBCR420 output, so that no
>   YCBCR 420 modes will be listed for sources which can't handle it.
>   A driver should set this variable if it wants to see YCBCR420 modes
>   in the modedb.
> 
> V5: Introduced the patch in series.
> V5-resend: Squashed two patches (validate YCBCR420 and add YCBCR420
> 	   identifier)
> 
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c         |  3 ++-
>  drivers/gpu/drm/drm_modes.c        | 28 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_probe_helper.c |  4 ++++
>  include/drm/drm_connector.h        |  9 +++++++++
>  include/drm/drm_edid.h             |  1 +
>  include/drm/drm_modes.h            |  5 +++++
>  6 files changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 10dab62..44be128 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2950,10 +2950,11 @@ u8 drm_match_cea_mode(const struct drm_display_mode *to_match)
>  }
>  EXPORT_SYMBOL(drm_match_cea_mode);
>  
> -static bool drm_valid_cea_vic(u8 vic)
> +bool drm_valid_cea_vic(u8 vic)
>  {
>  	return vic > 0 && vic < ARRAY_SIZE(edid_cea_modes);
>  }
> +EXPORT_SYMBOL(drm_valid_cea_vic);
>  
>  /**
>   * drm_get_cea_aspect_ratio - get the picture aspect ratio corresponding to
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index f2493b9..3b53c8e3 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -1083,6 +1083,34 @@ drm_mode_validate_size(const struct drm_display_mode *mode,
>  }
>  EXPORT_SYMBOL(drm_mode_validate_size);
>  
> +/**
> + * drm_mode_ycbcr420_only - add 'ycbcr420-only' modes only when allowed
> + * @mode: mode to check
> + * @connector: drm connector under action
> + *
> + * This function is a helper which can be used to filter out any YCBCR420
> + * only mode, when the source doesn't support it.
> + *
> + * Returns:
> + * The mode status
> + */
> +enum drm_mode_status
> +drm_mode_validate_ycbcr420(const struct drm_display_mode *mode,
> +			   struct drm_connector *connector)
> +{
> +	u8 vic = drm_match_cea_mode(mode);
> +	enum drm_mode_status status = MODE_OK;
> +	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
> +
> +	if (drm_valid_cea_vic(vic) && test_bit(vic, hdmi->y420_vdb_modes)) {

Still think the valid check is pointless. Skipping that would also avoid
having to make the function non-static (the EXPORT_SYMBOL there seems
unnecessary either way).

> +		if (!connector->ycbcr_420_allowed)
> +			status = MODE_NO_420;
> +	}
> +
> +	return status;
> +}
> +EXPORT_SYMBOL(drm_mode_validate_ycbcr420);
> +
>  #define MODE_STATUS(status) [MODE_ ## status + 3] = #status
>  
>  static const char * const drm_mode_status_names[] = {

^
This thing needs to be updated as well.

> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 00e6832..904966c 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -528,6 +528,10 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
>  		if (mode->status == MODE_OK)
>  			mode->status = drm_mode_validate_pipeline(mode,
>  								  connector);
> +
> +		if (mode->status == MODE_OK)
> +			mode->status = drm_mode_validate_ycbcr420(mode,
> +								  connector);
>  	}
>  
>  prune:
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index b3af8e3..225e092 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -746,6 +746,15 @@ struct drm_connector {
>  	bool interlace_allowed;
>  	bool doublescan_allowed;
>  	bool stereo_allowed;
> +
> +	/**
> +	 * @ycbcr_420_allowed : This bool indicates if this connector is
> +	 * capable of handling YCBCR 420 output. While parsing the EDID
> +	 * blocks, its very helpful to know, if the source is capable of
> +	 * handling YCBCR 420 outputs.
> +	 */
> +	bool ycbcr_420_allowed;
> +
>  	/**
>  	 * @registered: Is this connector exposed (registered) with userspace?
>  	 * Protected by @mutex.
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 89c0062..b55b2a7 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -477,4 +477,5 @@ void drm_edid_get_monitor_name(struct edid *edid, char *name,
>  struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
>  					   int hsize, int vsize, int fresh,
>  					   bool rb);
> +bool drm_valid_cea_vic(u8 vic);
>  #endif /* __DRM_EDID_H__ */
> diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
> index 94ac771..f8a1268 100644
> --- a/include/drm/drm_modes.h
> +++ b/include/drm/drm_modes.h
> @@ -80,6 +80,7 @@ struct videomode;
>   * @MODE_ONE_SIZE: only one resolution is supported
>   * @MODE_NO_REDUCED: monitor doesn't accept reduced blanking
>   * @MODE_NO_STEREO: stereo modes not supported
> + * @MODE_NO_420: ycbcr 420 modes not supported
>   * @MODE_STALE: mode has become stale
>   * @MODE_BAD: unspecified reason
>   * @MODE_ERROR: error condition
> @@ -124,6 +125,7 @@ enum drm_mode_status {
>  	MODE_ONE_SIZE,
>  	MODE_NO_REDUCED,
>  	MODE_NO_STEREO,
> +	MODE_NO_420,
>  	MODE_STALE = -3,
>  	MODE_BAD = -2,
>  	MODE_ERROR = -1
> @@ -496,6 +498,9 @@ bool drm_mode_equal_no_clocks_no_stereo(const struct drm_display_mode *mode1,
>  enum drm_mode_status drm_mode_validate_basic(const struct drm_display_mode *mode);
>  enum drm_mode_status drm_mode_validate_size(const struct drm_display_mode *mode,
>  					    int maxX, int maxY);
> +enum drm_mode_status
> +drm_mode_validate_ycbcr420(const struct drm_display_mode *mode,
> +			   struct drm_connector *connector);
>  void drm_mode_prune_invalid(struct drm_device *dev,
>  			    struct list_head *mode_list, bool verbose);
>  void drm_mode_sort(struct list_head *mode_list);
> -- 
> 2.7.4
> 
> _______________________________________________
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> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Ville Syrjälä
Intel OTC
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