Re: [PATCH 05/17] drm/msm/dp: add an API to indicate if sink supports VSC SDP

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 25/01/2024 21:38, Paloma Arellano wrote:
> YUV420 format is supported only in the VSC SDP packet and not through
> MSA. Hence add an API which indicates the sink support which can be used
> by the rest of the DP programming.

This API ideally should go to drm/display/drm_dp_helper.c

> 
> Signed-off-by: Paloma Arellano <quic_parellan@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dp/dp_display.c |  3 ++-
>   drivers/gpu/drm/msm/dp/dp_panel.c   | 35 +++++++++++++++++++++++++----
>   drivers/gpu/drm/msm/dp/dp_panel.h   |  1 +
>   3 files changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index ddac55f45a722..f6b3b6ca242f8 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1617,7 +1617,8 @@ void dp_bridge_mode_set(struct drm_bridge *drm_bridge,
>   		!!(dp_display->dp_mode.drm_mode.flags & DRM_MODE_FLAG_NHSYNC);
>   
>   	dp_display->dp_mode.out_fmt_is_yuv_420 =
> -		drm_mode_is_420_only(&dp->connector->display_info, adjusted_mode);
> +		drm_mode_is_420_only(&dp->connector->display_info, adjusted_mode) &&
> +		dp_panel_vsc_sdp_supported(dp_display->panel);
>   
>   	/* populate wide_bus_support to different layers */
>   	dp_display->ctrl->wide_bus_en =
> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
> index 127f6af995cd1..af7820b6d35ec 100644
> --- a/drivers/gpu/drm/msm/dp/dp_panel.c
> +++ b/drivers/gpu/drm/msm/dp/dp_panel.c
> @@ -17,6 +17,9 @@ struct dp_panel_private {
>   	struct dp_link *link;
>   	struct dp_catalog *catalog;
>   	bool panel_on;
> +	bool vsc_supported;
> +	u8 major;
> +	u8 minor;
>   };
>   
>   static void dp_panel_read_psr_cap(struct dp_panel_private *panel)
> @@ -43,9 +46,10 @@ static void dp_panel_read_psr_cap(struct dp_panel_private *panel)
>   static int dp_panel_read_dpcd(struct dp_panel *dp_panel)
>   {
>   	int rc;
> +	ssize_t rlen;
>   	struct dp_panel_private *panel;
>   	struct dp_link_info *link_info;
> -	u8 *dpcd, major, minor;
> +	u8 *dpcd, rx_feature;
>   
>   	panel = container_of(dp_panel, struct dp_panel_private, dp_panel);
>   	dpcd = dp_panel->dpcd;
> @@ -53,10 +57,19 @@ static int dp_panel_read_dpcd(struct dp_panel *dp_panel)
>   	if (rc)
>   		return rc;
>   
> +	rlen = drm_dp_dpcd_read(panel->aux, DP_DPRX_FEATURE_ENUMERATION_LIST, &rx_feature, 1);
> +	if (rlen != 1) {
> +		panel->vsc_supported = false;
> +		pr_debug("failed to read DP_DPRX_FEATURE_ENUMERATION_LIST\n");
> +	} else {
> +		panel->vsc_supported = !!(rx_feature & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED);
> +		pr_debug("vsc=%d\n", panel->vsc_supported);
> +	}
> +
>   	link_info = &dp_panel->link_info;
>   	link_info->revision = dpcd[DP_DPCD_REV];
> -	major = (link_info->revision >> 4) & 0x0f;
> -	minor = link_info->revision & 0x0f;
> +	panel->major = (link_info->revision >> 4) & 0x0f;
> +	panel->minor = link_info->revision & 0x0f;
>   
>   	link_info->rate = drm_dp_max_link_rate(dpcd);
>   	link_info->num_lanes = drm_dp_max_lane_count(dpcd);
> @@ -69,7 +82,7 @@ static int dp_panel_read_dpcd(struct dp_panel *dp_panel)
>   	if (link_info->rate > dp_panel->max_dp_link_rate)
>   		link_info->rate = dp_panel->max_dp_link_rate;
>   
> -	drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", major, minor);
> +	drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", panel->major, panel->minor);
>   	drm_dbg_dp(panel->drm_dev, "link_rate=%d\n", link_info->rate);
>   	drm_dbg_dp(panel->drm_dev, "lane_count=%d\n", link_info->num_lanes);
>   
> @@ -280,6 +293,20 @@ void dp_panel_tpg_config(struct dp_panel *dp_panel, bool enable)
>   	dp_catalog_panel_tpg_enable(catalog, &panel->dp_panel.dp_mode.drm_mode);
>   }
>   
> +bool dp_panel_vsc_sdp_supported(struct dp_panel *dp_panel)
> +{
> +	struct dp_panel_private *panel;
> +
> +	if (!dp_panel) {
> +		pr_err("invalid input\n");
> +		return false;
> +	}
> +
> +	panel = container_of(dp_panel, struct dp_panel_private, dp_panel);
> +
> +	return panel->major >= 1 && panel->minor >= 3 && panel->vsc_supported;
> +}
> +
>   void dp_panel_dump_regs(struct dp_panel *dp_panel)
>   {
>   	struct dp_catalog *catalog;
> diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
> index 6ec68be9f2366..590eca5ce304b 100644
> --- a/drivers/gpu/drm/msm/dp/dp_panel.h
> +++ b/drivers/gpu/drm/msm/dp/dp_panel.h
> @@ -66,6 +66,7 @@ int dp_panel_get_modes(struct dp_panel *dp_panel,
>   		struct drm_connector *connector);
>   void dp_panel_handle_sink_request(struct dp_panel *dp_panel);
>   void dp_panel_tpg_config(struct dp_panel *dp_panel, bool enable);
> +bool dp_panel_vsc_sdp_supported(struct dp_panel *dp_panel);
>   
>   /**
>    * is_link_rate_valid() - validates the link rate

-- 
With best wishes
Dmitry