Re: [PATCH v11 19/28] drm/connector: hdmi: Add RGB Quantization Range to the connector state

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

On Tue, Mar 26, 2024 at 04:40:23PM +0100, Maxime Ripard wrote:
> HDMI controller drivers will need to figure out the RGB range they need
> to configure based on a mode and property values. Let's expose that in
> the HDMI connector state so drivers can just use that value.
> 
> Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
> ---
>  drivers/gpu/drm/display/drm_hdmi_state_helper.c | 29 +++++++++++++++++++++++++
>  drivers/gpu/drm/drm_atomic.c                    |  1 +
>  include/drm/drm_connector.h                     |  6 +++++
>  3 files changed, 36 insertions(+)
> 
> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index c844cbeb675b..e693fe51abf5 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -49,10 +49,37 @@ connector_state_get_mode(const struct drm_connector_state *conn_state)
>  		return NULL;
>  
>  	return &crtc_state->mode;
>  }
>  
> +static bool hdmi_is_full_range(const struct drm_connector *connector,
> +			       const struct drm_connector_state *conn_state)
> +{
> +	const struct drm_display_info *display = &connector->display_info;

We call this 'info' everywhere else.

> +	const struct drm_display_mode *mode =
> +		connector_state_get_mode(conn_state);
> +
> +	/*
> +	 * The Broadcast RGB property only applies to RGB format, and
> +	 * i915 just assumes limited range for YCbCr output, so let's
> +	 * just do the same.
> +	 */
> +	if (conn_state->hdmi.output_format != HDMI_COLORSPACE_RGB)
> +		return false;
> +
> +	if (conn_state->hdmi.broadcast_rgb == DRM_HDMI_BROADCAST_RGB_FULL)
> +		return true;
> +
> +	if (conn_state->hdmi.broadcast_rgb == DRM_HDMI_BROADCAST_RGB_LIMITED)
> +		return false;
> +
> +	if (!display->is_hdmi)
> +		return true;
> +
> +	return drm_default_rgb_quant_range(mode) == HDMI_QUANTIZATION_RANGE_FULL ? true : false;

Pointless ?:

I'd probably use a switch statement to make
the whole thing a bit more clear.

I was pondering if we could also use this from i915. But
we'd have to turn the 'is_hdmi' part into a function
argument since we derive that from the current crtc state
rather than from the display info.

> +}
> +
>  static bool
>  sink_supports_format_bpc(const struct drm_connector *connector,
>  			 const struct drm_display_info *info,
>  			 const struct drm_display_mode *mode,
>  			 unsigned int format, unsigned int bpc)
> @@ -307,10 +334,12 @@ int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
>  		drm_atomic_get_new_connector_state(state, connector);
>  	const struct drm_display_mode *mode =
>  		connector_state_get_mode(new_conn_state);
>  	int ret;
>  
> +	new_conn_state->hdmi.is_full_range = hdmi_is_full_range(connector, new_conn_state);
> +
>  	ret = hdmi_compute_config(connector, new_conn_state, mode);
>  	if (ret)
>  		return ret;
>  
>  	if (old_conn_state->hdmi.broadcast_rgb != new_conn_state->hdmi.broadcast_rgb ||
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 3e57d98d8418..ec6c6beda5c9 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -1145,10 +1145,11 @@ static void drm_atomic_connector_print_state(struct drm_printer *p,
>  
>  	if (connector->connector_type == DRM_MODE_CONNECTOR_HDMIA ||
>  	    connector->connector_type == DRM_MODE_CONNECTOR_HDMIB) {
>  		drm_printf(p, "\tbroadcast_rgb=%s\n",
>  			   drm_hdmi_connector_get_broadcast_rgb_name(state->hdmi.broadcast_rgb));
> +		drm_printf(p, "\tis_full_range=%c\n", state->hdmi.is_full_range ? 'y' : 'n');
>  		drm_printf(p, "\toutput_bpc=%u\n", state->hdmi.output_bpc);
>  		drm_printf(p, "\toutput_format=%s\n",
>  			   drm_hdmi_connector_get_output_format_name(state->hdmi.output_format));
>  		drm_printf(p, "\ttmds_char_rate=%llu\n", state->hdmi.tmds_char_rate);
>  	}
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index a40eaf3a8ce4..f5e960e89de3 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -1068,10 +1068,16 @@ struct drm_connector_state {
>  		 * @broadcast_rgb: Connector property to pass the
>  		 * Broadcast RGB selection value.
>  		 */
>  		enum drm_hdmi_broadcast_rgb broadcast_rgb;
>  
> +		/**
> +		 * @is_full_range: Is the output supposed to use a full
> +		 * RGB Quantization Range or not?
> +		 */
> +		bool is_full_range;

I would say limited range is the exception so I would suggest
flagging that instead. Feels a bit weird to flag the normal
case. Maybe the name should also include 'rgb' to make it clear
it only applies to RGB.

> +
>  		/**
>  		 * @output_bpc: Bits per color channel to output.
>  		 */
>  		unsigned int output_bpc;
>  
> 
> -- 
> 2.44.0

-- 
Ville Syrjälä
Intel

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