[PATCH v5 2/2] drm/edid: Add function to parse EDID descriptors for adaptive sync limits

[Manasi Navare]

Hi Ville,

Please find answers to your concerns below:

On Mon, Mar 09, 2020 at 02:39:40PM -0700, Manasi Navare wrote:
> Adaptive Sync is a VESA feature so add a DRM core helper to parse
> the EDID's detailed descritors to obtain the adaptive sync monitor range.
> Store this info as part fo drm_display_info so it can be used
> across all drivers.
> This part of the code is stripped out of amdgpu's function
> amdgpu_dm_update_freesync_caps() to make it generic and be used
> across all DRM drivers
> 
> v5:
> * Use the renamed flags
> v4:
> * Use is_display_descriptor() (Ville)
> * Name the monitor range flags (Ville)
> v3:
> * Remove the edid parsing restriction for just DP (Nicholas)
> * Use drm_for_each_detailed_block (Ville)
> * Make the drm_get_adaptive_sync_range function static (Harry, Jani)
> v2:
> * Change vmin and vmax to use u8 (Ville)
> * Dont store pixel clock since that is just a max dotclock
> and not related to VRR mode (Manasi)
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Harry Wentland <harry.wentland at amd.com>
> Cc: Clinton A Taylor <clinton.a.taylor at intel.com>
> Cc: Kazlauskas Nicholas <Nicholas.Kazlauskas at amd.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
> ---
>  drivers/gpu/drm/drm_edid.c  | 44 +++++++++++++++++++++++++++++++++++++
>  include/drm/drm_connector.h | 22 +++++++++++++++++++
>  2 files changed, 66 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index ad41764a4ebe..24b76ae58fdd 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4938,6 +4938,47 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
>  	}
>  }
>  
> +static
> +void get_adaptive_sync_range(struct detailed_timing *timing,
> +			     void *info_adaptive_sync)
> +{
> +	struct drm_adaptive_sync_info *adaptive_sync = info_adaptive_sync;
> +	const struct detailed_non_pixel *data = &timing->data.other_data;
> +	const struct detailed_data_monitor_range *range = &data->data.range;
> +
> +	if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_MONITOR_RANGE))
> +		return;
> +
> +	/*
> +	 * Check for flag range limits only. If flag == 1 then
> +	 * no additional timing information provided.
> +	 * Default GTF, GTF Secondary curve and CVT are not
> +	 * supported
> +	 */
> +	if (range->flags != DRM_EDID_RANGE_LIMITS_ONLY_FLAG)
> +		return;
> +
> +	adaptive_sync->min_vfreq = range->min_vfreq;
> +	adaptive_sync->max_vfreq = range->max_vfreq;
> +}
> +
> +static
> +void drm_get_adaptive_sync_range(struct drm_connector *connector,
> +				 const struct edid *edid)
> +{
> +	struct drm_display_info *info = &connector->display_info;
> +
> +	if (!version_greater(edid, 1, 1))
> +		return;
> +
> +	drm_for_each_detailed_block((u8 *)edid, get_adaptive_sync_range,
> +				    &info->adaptive_sync);

Some functions like get_monitor_name also pass something like &edid_name, I dont
think there is any specific convention of the argument name to be passed.

> +
> +	DRM_DEBUG_KMS("Adaptive Sync refresh rate range is %d Hz - %d Hz\n",
> +		      info->adaptive_sync.min_vfreq,
> +		      info->adaptive_sync.max_vfreq);

Yes I agree that this is just a monitor range and unless the dpcd ignore msa bit is set
and the range is atleast 10Hz apart , it might not be vrr range.

Would you prefer renaming this info->adaptive_sync as info->monitor_range ? Or
should i just print it out as Monitor range is in the dmesg but leave the info->adaptive_sync
naming as is?

Manasi

> +}
> +
>  /* A connector has no EDID information, so we've got no EDID to compute quirks from. Reset
>   * all of the values which would have been set from EDID
>   */
> @@ -4960,6 +5001,7 @@ drm_reset_display_info(struct drm_connector *connector)
>  	memset(&info->hdmi, 0, sizeof(info->hdmi));
>  
>  	info->non_desktop = 0;
> +	memset(&info->adaptive_sync, 0, sizeof(info->adaptive_sync));
>  }
>  
>  u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edid)
> @@ -4975,6 +5017,8 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
>  
>  	info->non_desktop = !!(quirks & EDID_QUIRK_NON_DESKTOP);
>  
> +	drm_get_adaptive_sync_range(connector, edid);
> +
>  	DRM_DEBUG_KMS("non_desktop set to %d\n", info->non_desktop);
>  
>  	if (edid->revision < 3)
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 0df7a95ca5d9..2b22c0fa42c4 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -254,6 +254,23 @@ enum drm_panel_orientation {
>  	DRM_MODE_PANEL_ORIENTATION_RIGHT_UP,
>  };
>  
> +/**
> + * struct drm_adaptive_sync_info - Panel's Adaptive Sync capabilities for
> + * &drm_display_info
> + *
> + * This struct is used to store a Panel's Adaptive Sync capabilities
> + * as parsed from EDID's detailed monitor range descriptor block.
> + *
> + * @min_vfreq: This is the min supported refresh rate in Hz from
> + *             EDID's detailed monitor range.
> + * @max_vfreq: This is the max supported refresh rate in Hz from
> + *             EDID's detailed monitor range
> + */
> +struct drm_adaptive_sync_info {
> +	u8 min_vfreq;
> +	u8 max_vfreq;
> +};
> +
>  /*
>   * This is a consolidated colorimetry list supported by HDMI and
>   * DP protocol standard. The respective connectors will register
> @@ -473,6 +490,11 @@ struct drm_display_info {
>  	 * @non_desktop: Non desktop display (HMD).
>  	 */
>  	bool non_desktop;
> +
> +	/**
> +	 * @adaptive_sync: Adaptive Sync capabilities of the DP/eDP sink
> +	 */
> +	struct drm_adaptive_sync_info adaptive_sync;
>  };
>  
>  int drm_display_info_set_bus_formats(struct drm_display_info *info,
> -- 
> 2.19.1
>