linux-kernel - Re: [PATCH 2/3] drm/connector: hdmi: Add support for YUV420 format verification

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Message-ID: <20241202-determined-sloppy-impala-2ca0f1@houat>
Date: Mon, 2 Dec 2024 11:50:01 +0100
From: Maxime Ripard <mripard@...nel.org>
To: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, kernel@...labora.com, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] drm/connector: hdmi: Add support for YUV420 format
 verification

On Sat, Nov 30, 2024 at 01:56:33AM +0200, Cristian Ciocaltea wrote:
> Provide the necessary constraints verification in
> sink_supports_format_bpc() in order to support handling of YUV420
> output format.
> 
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
> ---
>  drivers/gpu/drm/display/drm_hdmi_state_helper.c | 40 +++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 0cbcee7e77cd8dff387044487ce28ee5748f5587..3a55881a544a519bb1254968db891c814f831a0f 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -3,6 +3,7 @@
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_connector.h>
>  #include <drm/drm_edid.h>
> +#include <drm/drm_modes.h>
>  #include <drm/drm_print.h>
>  
>  #include <drm/display/drm_hdmi_helper.h>
> @@ -114,6 +115,12 @@ sink_supports_format_bpc(const struct drm_connector *connector,
>  		return false;
>  	}
>  
> +	if (drm_mode_is_420_only(info, mode) && format != HDMI_COLORSPACE_YUV420) {
> +		drm_dbg_kms(dev, "%s format unsupported by the sink for VIC%u.\n",
> +			    drm_hdmi_connector_get_output_format_name(format), vic);
> +		return false;
> +	}
> +
>  	switch (format) {
>  	case HDMI_COLORSPACE_RGB:
>  		drm_dbg_kms(dev, "RGB Format, checking the constraints.\n");
> @@ -144,9 +151,36 @@ sink_supports_format_bpc(const struct drm_connector *connector,
>  		return true;
>  
>  	case HDMI_COLORSPACE_YUV420:
> -		/* TODO: YUV420 is unsupported at the moment. */
> -		drm_dbg_kms(dev, "YUV420 format isn't supported yet.\n");
> -		return false;
> +		drm_dbg_kms(dev, "YUV420 format, checking the constraints.\n");
> +
> +		if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR420)) {
> +			drm_dbg_kms(dev, "Sink doesn't support YUV420.\n");
> +			return false;
> +		}
> +
> +		if (!drm_mode_is_420(info, mode)) {
> +			drm_dbg_kms(dev, "Sink doesn't support YUV420 for VIC%u.\n", vic);
> +			return false;
> +		}
> +
> +		if (bpc == 10 && !(info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_30)) {
> +			drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
> +			return false;
> +		}
> +
> +		if (bpc == 12 && !(info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_36)) {
> +			drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
> +			return false;
> +		}
> +
> +		if (bpc == 16 && !(info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_48)) {
> +			drm_dbg_kms(dev, "16 BPC but sink doesn't support Deep Color 48.\n");
> +			return false;
> +		}
> +
> +		drm_dbg_kms(dev, "YUV420 format supported in that configuration.\n");
> +
> +		return true;

We also need to check whether the source supports it or not.

Maxime

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