diff mbox series

[v11,15/28] drm/connector: hdmi: Compute bpc and format automatically

Message ID 20240326-kms-hdmi-connector-state-v11-15-c5680ffcf261@kernel.org (mailing list archive)
State New, archived
Headers show
Series drm/connector: Create HDMI Connector infrastructure | expand

Commit Message

Maxime Ripard March 26, 2024, 3:40 p.m. UTC
Now that we have all the infrastructure needed, we can add some code
that will, for a given connector state and mode, compute the best output
format and bpc.

The algorithm is equivalent to the one already found in i915 and vc4.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/display/drm_hdmi_state_helper.c    | 197 ++++++++++++++++++++-
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c |  25 ++-
 2 files changed, 210 insertions(+), 12 deletions(-)

Comments

Ville Syrjälä April 16, 2024, 1:50 p.m. UTC | #1
On Tue, Mar 26, 2024 at 04:40:19PM +0100, Maxime Ripard wrote:
> Now that we have all the infrastructure needed, we can add some code
> that will, for a given connector state and mode, compute the best output
> format and bpc.
> 
> The algorithm is equivalent to the one already found in i915 and vc4.
> 
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
> ---
>  drivers/gpu/drm/display/drm_hdmi_state_helper.c    | 197 ++++++++++++++++++++-
>  drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c |  25 ++-
>  2 files changed, 210 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 063421835dba..b9bc0fb027ea 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -1,9 +1,11 @@
>  // SPDX-License-Identifier: MIT
>  
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_connector.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_print.h>
>  
>  #include <drm/display/drm_hdmi_helper.h>
>  #include <drm/display/drm_hdmi_state_helper.h>
>  
>  /**
> @@ -46,10 +48,110 @@ connector_state_get_mode(const struct drm_connector_state *conn_state)
>  		return NULL;
>  
>  	return &crtc_state->mode;
>  }
>  
> +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)
> +{
> +	struct drm_device *dev = connector->dev;
> +	u8 vic = drm_match_cea_mode(mode);
> +
> +	/*
> +	 * CTA-861-F, section 5.4 - Color Coding & Quantization states
> +	 * that the bpc must be 8, 10, 12 or 16 except for the default
> +	 * 640x480 VIC1 where the value must be 8.
> +	 *
> +	 * The definition of default here is ambiguous but the spec
> +	 * refers to VIC1 being the default timing in several occasions
> +	 * so our understanding is that for the default timing (ie,
> +	 * VIC1), the bpc must be 8.
> +	 */
> +	if (vic == 1 && bpc != 8) {
> +		drm_dbg_kms(dev, "VIC1 requires a bpc of 8, got %u\n", bpc);
> +		return false;
> +	}
> +
> +	if (!info->is_hdmi &&
> +	    (format != HDMI_COLORSPACE_RGB || bpc != 8)) {
> +		drm_dbg_kms(dev, "DVI Monitors require an RGB output at 8 bpc\n");
> +		return false;
> +	}
> +
> +	if (!(connector->hdmi.supported_formats & BIT(format))) {

These are the capabilities of the souce I take it?

> +		drm_dbg_kms(dev, "%s format unsupported by the connector.\n",
> +			    drm_hdmi_connector_get_output_format_name(format));
> +		return false;
> +	}
> +
> +	switch (format) {
> +	case HDMI_COLORSPACE_RGB:
> +		drm_dbg_kms(dev, "RGB Format, checking the constraints.\n");
> +
> +		if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
> +			return false;

and this is the sink.

Maybe we should use the same bits for both? Anyways, that seems like
material for a followup series.

> +
> +		if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
> +			drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
> +			return false;
> +		}
> +
> +		if (bpc == 12 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_36)) {
> +			drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
> +			return false;
> +		}
> +
> +		drm_dbg_kms(dev, "RGB format supported in that configuration.\n");
> +
> +		return true;
> +
> +	case HDMI_COLORSPACE_YUV422:
> +		drm_dbg_kms(dev, "YUV422 format, checking the constraints.\n");
> +
> +		if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR422)) {
> +			drm_dbg_kms(dev, "Sink doesn't support YUV422.\n");
> +			return false;
> +		}
> +
> +		if (bpc != 12) {
> +			drm_dbg_kms(dev, "YUV422 only supports 12 bpc.\n");
> +			return false;
> +		}

Did something change around here from the last time?

> +
> +		drm_dbg_kms(dev, "YUV422 format supported in that configuration.\n");
> +
> +		return true;
> +
> +	case HDMI_COLORSPACE_YUV444:
> +		drm_dbg_kms(dev, "YUV444 format, checking the constraints.\n");
> +
> +		if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR444)) {
> +			drm_dbg_kms(dev, "Sink doesn't support YUV444.\n");
> +			return false;
> +		}
> +
> +		if (bpc == 10 && !(info->edid_hdmi_ycbcr444_dc_modes & DRM_EDID_HDMI_DC_30)) {
> +			drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
> +			return false;
> +		}
> +
> +		if (bpc == 12 && !(info->edid_hdmi_ycbcr444_dc_modes & DRM_EDID_HDMI_DC_36)) {
> +			drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
> +			return false;
> +		}
> +
> +		drm_dbg_kms(dev, "YUV444 format supported in that configuration.\n");
> +
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
>  static enum drm_mode_status
>  hdmi_clock_valid(const struct drm_connector *connector,
>  		 const struct drm_display_mode *mode,
>  		 unsigned long long clock)
>  {
> @@ -90,10 +192,101 @@ hdmi_compute_clock(const struct drm_connector *connector,
>  	conn_state->hdmi.tmds_char_rate = clock;
>  
>  	return 0;
>  }
>  
> +static bool
> +hdmi_try_format_bpc(const struct drm_connector *connector,
> +		    struct drm_connector_state *conn_state,
> +		    const struct drm_display_mode *mode,
> +		    unsigned int bpc, enum hdmi_colorspace fmt)
> +{
> +	const struct drm_display_info *info = &connector->display_info;
> +	struct drm_device *dev = connector->dev;
> +	int ret;
> +
> +	drm_dbg_kms(dev, "Trying %s output format\n",
> +		    drm_hdmi_connector_get_output_format_name(fmt));
> +
> +	if (!sink_supports_format_bpc(connector, info, mode, fmt, bpc)) {
> +		drm_dbg_kms(dev, "%s output format not supported with %u bpc\n",
> +			    drm_hdmi_connector_get_output_format_name(fmt),
> +			    bpc);
> +		return false;
> +	}
> +
> +	ret = hdmi_compute_clock(connector, conn_state, mode, bpc, fmt);
> +	if (ret) {
> +		drm_dbg_kms(dev, "Couldn't compute clock for %s output format and %u bpc\n",
> +			    drm_hdmi_connector_get_output_format_name(fmt),
> +			    bpc);
> +		return false;
> +	}
> +
> +	drm_dbg_kms(dev, "%s output format supported with %u (TMDS char rate: %llu Hz)\n",
> +		    drm_hdmi_connector_get_output_format_name(fmt),
> +		    bpc, conn_state->hdmi.tmds_char_rate);
> +
> +	return true;
> +}
> +
> +static int
> +hdmi_compute_format(const struct drm_connector *connector,
> +		    struct drm_connector_state *conn_state,
> +		    const struct drm_display_mode *mode,
> +		    unsigned int bpc)
> +{
> +	struct drm_device *dev = connector->dev;
> +
> +	/*
> +	 * TODO: Add support for YCbCr420 output for HDMI 2.0 capable
> +	 * devices, for modes that only support YCbCr420.
> +	 */
> +	if (hdmi_try_format_bpc(connector, conn_state, mode, bpc, HDMI_COLORSPACE_RGB)) {
> +		conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
> +		return 0;
> +	}
> +
> +	drm_dbg_kms(dev, "Failed. No Format Supported for that bpc count.\n");
> +
> +	return -EINVAL;
> +}
> +
> +static int
> +hdmi_compute_config(const struct drm_connector *connector,
> +		    struct drm_connector_state *conn_state,
> +		    const struct drm_display_mode *mode)
> +{
> +	struct drm_device *dev = connector->dev;
> +	unsigned int max_bpc = clamp_t(unsigned int,
> +				       conn_state->max_bpc,
> +				       8, connector->max_bpc);
> +	unsigned int bpc;
> +	int ret;
> +
> +	for (bpc = max_bpc; bpc >= 8; bpc -= 2) {
> +		drm_dbg_kms(dev, "Trying with a %d bpc output\n", bpc);
> +
> +		ret = hdmi_compute_format(connector, conn_state, mode, bpc);
> +		if (ret)
> +			continue;
> +
> +		conn_state->hdmi.output_bpc = bpc;
> +
> +		drm_dbg_kms(dev,
> +			    "Mode %ux%u @ %uHz: Found configuration: bpc: %u, fmt: %s, clock: %llu\n",
> +			    mode->hdisplay, mode->vdisplay, drm_mode_vrefresh(mode),
> +			    conn_state->hdmi.output_bpc,
> +			    drm_hdmi_connector_get_output_format_name(conn_state->hdmi.output_format),
> +			    conn_state->hdmi.tmds_char_rate);
> +
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
>  /**
>   * drm_atomic_helper_connector_hdmi_check() - Helper to check HDMI connector atomic state
>   * @connector: DRM Connector
>   * @state: the DRM State object
>   *
> @@ -113,13 +306,11 @@ 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;
>  
> -	ret = hdmi_compute_clock(connector, new_conn_state, mode,
> -				 new_conn_state->hdmi.output_bpc,
> -				 new_conn_state->hdmi.output_format);
> +	ret = hdmi_compute_config(connector, new_conn_state, mode);
>  	if (ret)
>  		return ret;
>  
>  	if (old_conn_state->hdmi.output_bpc != new_conn_state->hdmi.output_bpc ||
>  	    old_conn_state->hdmi.output_format != new_conn_state->hdmi.output_format) {
> diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
> index ead998a691e7..a49a544d7b49 100644
> --- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
> +++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
> @@ -70,13 +70,10 @@ static int light_up_connector(struct kunit *test,
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
>  
>  	conn_state = drm_atomic_get_connector_state(state, connector);
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
>  
> -	conn_state->hdmi.output_bpc = connector->max_bpc;
> -	conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
> -
>  	ret = drm_atomic_set_crtc_for_connector(conn_state, crtc);
>  	KUNIT_EXPECT_EQ(test, ret, 0);
>  
>  	crtc_state = drm_atomic_get_crtc_state(state, crtc);
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
> @@ -251,14 +248,19 @@ static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
>  	priv = drm_atomic_helper_connector_hdmi_init(test,
>  						     BIT(HDMI_COLORSPACE_RGB),
>  						     10);
>  	KUNIT_ASSERT_NOT_NULL(test, priv);
>  
> +	conn = &priv->connector;
> +	ret = set_connector_edid(test, conn,
> +				 test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz,
> +				 ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz));
> +	KUNIT_ASSERT_EQ(test, ret, 0);
> +
>  	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
>  
> -	conn = &priv->connector;
>  	preferred = find_preferred_mode(conn);
>  	KUNIT_ASSERT_NOT_NULL(test, preferred);
>  
>  	drm = &priv->drm;
>  	crtc = priv->crtc;
> @@ -272,15 +274,15 @@ static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, new_conn_state);
>  
>  	old_conn_state = drm_atomic_get_old_connector_state(state, conn);
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, old_conn_state);
>  
> -	new_conn_state->hdmi.output_bpc = 8;
> +	new_conn_state->max_requested_bpc = 8;
>  
>  	KUNIT_ASSERT_NE(test,
> -			old_conn_state->hdmi.output_bpc,
> -			new_conn_state->hdmi.output_bpc);
> +			old_conn_state->max_requested_bpc,
> +			new_conn_state->max_requested_bpc);
>  
>  	ret = drm_atomic_check_only(state);
>  	KUNIT_ASSERT_EQ(test, ret, 0);
>  
>  	old_conn_state = drm_atomic_get_old_connector_state(state, conn);
> @@ -320,14 +322,19 @@ static void drm_test_check_output_bpc_crtc_mode_not_changed(struct kunit *test)
>  	priv = drm_atomic_helper_connector_hdmi_init(test,
>  						     BIT(HDMI_COLORSPACE_RGB),
>  						     10);
>  	KUNIT_ASSERT_NOT_NULL(test, priv);
>  
> +	conn = &priv->connector;
> +	ret = set_connector_edid(test, conn,
> +				 test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz,
> +				 ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz));
> +	KUNIT_ASSERT_EQ(test, ret, 0);
> +
>  	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
>  	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
>  
> -	conn = &priv->connector;
>  	preferred = find_preferred_mode(conn);
>  	KUNIT_ASSERT_NOT_NULL(test, preferred);
>  
>  	drm = &priv->drm;
>  	crtc = priv->crtc;
> @@ -670,11 +677,11 @@ static void drm_test_check_format_value(struct kunit *test)
>  						     8);
>  	KUNIT_ASSERT_NOT_NULL(test, priv);
>  
>  	conn = &priv->connector;
>  	conn_state = conn->state;
> -	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, HDMI_COLORSPACE_RGB);
> +	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, 0);
>  }
>  
>  /*
>   * Test that the value of the output format property out of reset is set
>   * to 0, and will be computed at atomic_check time.
> 
> -- 
> 2.44.0
Maxime Ripard April 19, 2024, 1:01 p.m. UTC | #2
On Tue, Apr 16, 2024 at 04:50:58PM +0300, Ville Syrjälä wrote:
> On Tue, Mar 26, 2024 at 04:40:19PM +0100, Maxime Ripard wrote:
> > Now that we have all the infrastructure needed, we can add some code
> > that will, for a given connector state and mode, compute the best output
> > format and bpc.
> > 
> > The algorithm is equivalent to the one already found in i915 and vc4.
> > 
> > Signed-off-by: Maxime Ripard <mripard@kernel.org>
> > ---
> >  drivers/gpu/drm/display/drm_hdmi_state_helper.c    | 197 ++++++++++++++++++++-
> >  drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c |  25 ++-
> >  2 files changed, 210 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > index 063421835dba..b9bc0fb027ea 100644
> > --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> > @@ -1,9 +1,11 @@
> >  // SPDX-License-Identifier: MIT
> >  
> >  #include <drm/drm_atomic.h>
> >  #include <drm/drm_connector.h>
> > +#include <drm/drm_edid.h>
> > +#include <drm/drm_print.h>
> >  
> >  #include <drm/display/drm_hdmi_helper.h>
> >  #include <drm/display/drm_hdmi_state_helper.h>
> >  
> >  /**
> > @@ -46,10 +48,110 @@ connector_state_get_mode(const struct drm_connector_state *conn_state)
> >  		return NULL;
> >  
> >  	return &crtc_state->mode;
> >  }
> >  
> > +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)
> > +{
> > +	struct drm_device *dev = connector->dev;
> > +	u8 vic = drm_match_cea_mode(mode);
> > +
> > +	/*
> > +	 * CTA-861-F, section 5.4 - Color Coding & Quantization states
> > +	 * that the bpc must be 8, 10, 12 or 16 except for the default
> > +	 * 640x480 VIC1 where the value must be 8.
> > +	 *
> > +	 * The definition of default here is ambiguous but the spec
> > +	 * refers to VIC1 being the default timing in several occasions
> > +	 * so our understanding is that for the default timing (ie,
> > +	 * VIC1), the bpc must be 8.
> > +	 */
> > +	if (vic == 1 && bpc != 8) {
> > +		drm_dbg_kms(dev, "VIC1 requires a bpc of 8, got %u\n", bpc);
> > +		return false;
> > +	}
> > +
> > +	if (!info->is_hdmi &&
> > +	    (format != HDMI_COLORSPACE_RGB || bpc != 8)) {
> > +		drm_dbg_kms(dev, "DVI Monitors require an RGB output at 8 bpc\n");
> > +		return false;
> > +	}
> > +
> > +	if (!(connector->hdmi.supported_formats & BIT(format))) {
> 
> These are the capabilities of the souce I take it?
>
> > +		drm_dbg_kms(dev, "%s format unsupported by the connector.\n",
> > +			    drm_hdmi_connector_get_output_format_name(format));
> > +		return false;
> > +	}
> > +
> > +	switch (format) {
> > +	case HDMI_COLORSPACE_RGB:
> > +		drm_dbg_kms(dev, "RGB Format, checking the constraints.\n");
> > +
> > +		if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
> > +			return false;
> 
> and this is the sink.
>
> Maybe we should use the same bits for both? Anyways, that seems like
> material for a followup series.

Ack

> > +
> > +		if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
> > +			drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
> > +			return false;
> > +		}
> > +
> > +		if (bpc == 12 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_36)) {
> > +			drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
> > +			return false;
> > +		}
> > +
> > +		drm_dbg_kms(dev, "RGB format supported in that configuration.\n");
> > +
> > +		return true;
> > +
> > +	case HDMI_COLORSPACE_YUV422:
> > +		drm_dbg_kms(dev, "YUV422 format, checking the constraints.\n");
> > +
> > +		if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR422)) {
> > +			drm_dbg_kms(dev, "Sink doesn't support YUV422.\n");
> > +			return false;
> > +		}
> > +
> > +		if (bpc != 12) {
> > +			drm_dbg_kms(dev, "YUV422 only supports 12 bpc.\n");
> > +			return false;
> > +		}
> 
> Did something change around here from the last time?

The format selection code now prefers to select a lower bpc rather than
another format, which is what you asked for in the previous version.
diff mbox series

Patch

diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
index 063421835dba..b9bc0fb027ea 100644
--- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
@@ -1,9 +1,11 @@ 
 // SPDX-License-Identifier: MIT
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_connector.h>
+#include <drm/drm_edid.h>
+#include <drm/drm_print.h>
 
 #include <drm/display/drm_hdmi_helper.h>
 #include <drm/display/drm_hdmi_state_helper.h>
 
 /**
@@ -46,10 +48,110 @@  connector_state_get_mode(const struct drm_connector_state *conn_state)
 		return NULL;
 
 	return &crtc_state->mode;
 }
 
+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)
+{
+	struct drm_device *dev = connector->dev;
+	u8 vic = drm_match_cea_mode(mode);
+
+	/*
+	 * CTA-861-F, section 5.4 - Color Coding & Quantization states
+	 * that the bpc must be 8, 10, 12 or 16 except for the default
+	 * 640x480 VIC1 where the value must be 8.
+	 *
+	 * The definition of default here is ambiguous but the spec
+	 * refers to VIC1 being the default timing in several occasions
+	 * so our understanding is that for the default timing (ie,
+	 * VIC1), the bpc must be 8.
+	 */
+	if (vic == 1 && bpc != 8) {
+		drm_dbg_kms(dev, "VIC1 requires a bpc of 8, got %u\n", bpc);
+		return false;
+	}
+
+	if (!info->is_hdmi &&
+	    (format != HDMI_COLORSPACE_RGB || bpc != 8)) {
+		drm_dbg_kms(dev, "DVI Monitors require an RGB output at 8 bpc\n");
+		return false;
+	}
+
+	if (!(connector->hdmi.supported_formats & BIT(format))) {
+		drm_dbg_kms(dev, "%s format unsupported by the connector.\n",
+			    drm_hdmi_connector_get_output_format_name(format));
+		return false;
+	}
+
+	switch (format) {
+	case HDMI_COLORSPACE_RGB:
+		drm_dbg_kms(dev, "RGB Format, checking the constraints.\n");
+
+		if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
+			return false;
+
+		if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
+			drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
+			return false;
+		}
+
+		if (bpc == 12 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_36)) {
+			drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
+			return false;
+		}
+
+		drm_dbg_kms(dev, "RGB format supported in that configuration.\n");
+
+		return true;
+
+	case HDMI_COLORSPACE_YUV422:
+		drm_dbg_kms(dev, "YUV422 format, checking the constraints.\n");
+
+		if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR422)) {
+			drm_dbg_kms(dev, "Sink doesn't support YUV422.\n");
+			return false;
+		}
+
+		if (bpc != 12) {
+			drm_dbg_kms(dev, "YUV422 only supports 12 bpc.\n");
+			return false;
+		}
+
+		drm_dbg_kms(dev, "YUV422 format supported in that configuration.\n");
+
+		return true;
+
+	case HDMI_COLORSPACE_YUV444:
+		drm_dbg_kms(dev, "YUV444 format, checking the constraints.\n");
+
+		if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR444)) {
+			drm_dbg_kms(dev, "Sink doesn't support YUV444.\n");
+			return false;
+		}
+
+		if (bpc == 10 && !(info->edid_hdmi_ycbcr444_dc_modes & DRM_EDID_HDMI_DC_30)) {
+			drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
+			return false;
+		}
+
+		if (bpc == 12 && !(info->edid_hdmi_ycbcr444_dc_modes & DRM_EDID_HDMI_DC_36)) {
+			drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
+			return false;
+		}
+
+		drm_dbg_kms(dev, "YUV444 format supported in that configuration.\n");
+
+		return true;
+	}
+
+	return false;
+}
+
 static enum drm_mode_status
 hdmi_clock_valid(const struct drm_connector *connector,
 		 const struct drm_display_mode *mode,
 		 unsigned long long clock)
 {
@@ -90,10 +192,101 @@  hdmi_compute_clock(const struct drm_connector *connector,
 	conn_state->hdmi.tmds_char_rate = clock;
 
 	return 0;
 }
 
+static bool
+hdmi_try_format_bpc(const struct drm_connector *connector,
+		    struct drm_connector_state *conn_state,
+		    const struct drm_display_mode *mode,
+		    unsigned int bpc, enum hdmi_colorspace fmt)
+{
+	const struct drm_display_info *info = &connector->display_info;
+	struct drm_device *dev = connector->dev;
+	int ret;
+
+	drm_dbg_kms(dev, "Trying %s output format\n",
+		    drm_hdmi_connector_get_output_format_name(fmt));
+
+	if (!sink_supports_format_bpc(connector, info, mode, fmt, bpc)) {
+		drm_dbg_kms(dev, "%s output format not supported with %u bpc\n",
+			    drm_hdmi_connector_get_output_format_name(fmt),
+			    bpc);
+		return false;
+	}
+
+	ret = hdmi_compute_clock(connector, conn_state, mode, bpc, fmt);
+	if (ret) {
+		drm_dbg_kms(dev, "Couldn't compute clock for %s output format and %u bpc\n",
+			    drm_hdmi_connector_get_output_format_name(fmt),
+			    bpc);
+		return false;
+	}
+
+	drm_dbg_kms(dev, "%s output format supported with %u (TMDS char rate: %llu Hz)\n",
+		    drm_hdmi_connector_get_output_format_name(fmt),
+		    bpc, conn_state->hdmi.tmds_char_rate);
+
+	return true;
+}
+
+static int
+hdmi_compute_format(const struct drm_connector *connector,
+		    struct drm_connector_state *conn_state,
+		    const struct drm_display_mode *mode,
+		    unsigned int bpc)
+{
+	struct drm_device *dev = connector->dev;
+
+	/*
+	 * TODO: Add support for YCbCr420 output for HDMI 2.0 capable
+	 * devices, for modes that only support YCbCr420.
+	 */
+	if (hdmi_try_format_bpc(connector, conn_state, mode, bpc, HDMI_COLORSPACE_RGB)) {
+		conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
+		return 0;
+	}
+
+	drm_dbg_kms(dev, "Failed. No Format Supported for that bpc count.\n");
+
+	return -EINVAL;
+}
+
+static int
+hdmi_compute_config(const struct drm_connector *connector,
+		    struct drm_connector_state *conn_state,
+		    const struct drm_display_mode *mode)
+{
+	struct drm_device *dev = connector->dev;
+	unsigned int max_bpc = clamp_t(unsigned int,
+				       conn_state->max_bpc,
+				       8, connector->max_bpc);
+	unsigned int bpc;
+	int ret;
+
+	for (bpc = max_bpc; bpc >= 8; bpc -= 2) {
+		drm_dbg_kms(dev, "Trying with a %d bpc output\n", bpc);
+
+		ret = hdmi_compute_format(connector, conn_state, mode, bpc);
+		if (ret)
+			continue;
+
+		conn_state->hdmi.output_bpc = bpc;
+
+		drm_dbg_kms(dev,
+			    "Mode %ux%u @ %uHz: Found configuration: bpc: %u, fmt: %s, clock: %llu\n",
+			    mode->hdisplay, mode->vdisplay, drm_mode_vrefresh(mode),
+			    conn_state->hdmi.output_bpc,
+			    drm_hdmi_connector_get_output_format_name(conn_state->hdmi.output_format),
+			    conn_state->hdmi.tmds_char_rate);
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 /**
  * drm_atomic_helper_connector_hdmi_check() - Helper to check HDMI connector atomic state
  * @connector: DRM Connector
  * @state: the DRM State object
  *
@@ -113,13 +306,11 @@  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;
 
-	ret = hdmi_compute_clock(connector, new_conn_state, mode,
-				 new_conn_state->hdmi.output_bpc,
-				 new_conn_state->hdmi.output_format);
+	ret = hdmi_compute_config(connector, new_conn_state, mode);
 	if (ret)
 		return ret;
 
 	if (old_conn_state->hdmi.output_bpc != new_conn_state->hdmi.output_bpc ||
 	    old_conn_state->hdmi.output_format != new_conn_state->hdmi.output_format) {
diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
index ead998a691e7..a49a544d7b49 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -70,13 +70,10 @@  static int light_up_connector(struct kunit *test,
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
 
 	conn_state = drm_atomic_get_connector_state(state, connector);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
 
-	conn_state->hdmi.output_bpc = connector->max_bpc;
-	conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
-
 	ret = drm_atomic_set_crtc_for_connector(conn_state, crtc);
 	KUNIT_EXPECT_EQ(test, ret, 0);
 
 	crtc_state = drm_atomic_get_crtc_state(state, crtc);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
@@ -251,14 +248,19 @@  static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
 	priv = drm_atomic_helper_connector_hdmi_init(test,
 						     BIT(HDMI_COLORSPACE_RGB),
 						     10);
 	KUNIT_ASSERT_NOT_NULL(test, priv);
 
+	conn = &priv->connector;
+	ret = set_connector_edid(test, conn,
+				 test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz,
+				 ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz));
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
 
-	conn = &priv->connector;
 	preferred = find_preferred_mode(conn);
 	KUNIT_ASSERT_NOT_NULL(test, preferred);
 
 	drm = &priv->drm;
 	crtc = priv->crtc;
@@ -272,15 +274,15 @@  static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, new_conn_state);
 
 	old_conn_state = drm_atomic_get_old_connector_state(state, conn);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, old_conn_state);
 
-	new_conn_state->hdmi.output_bpc = 8;
+	new_conn_state->max_requested_bpc = 8;
 
 	KUNIT_ASSERT_NE(test,
-			old_conn_state->hdmi.output_bpc,
-			new_conn_state->hdmi.output_bpc);
+			old_conn_state->max_requested_bpc,
+			new_conn_state->max_requested_bpc);
 
 	ret = drm_atomic_check_only(state);
 	KUNIT_ASSERT_EQ(test, ret, 0);
 
 	old_conn_state = drm_atomic_get_old_connector_state(state, conn);
@@ -320,14 +322,19 @@  static void drm_test_check_output_bpc_crtc_mode_not_changed(struct kunit *test)
 	priv = drm_atomic_helper_connector_hdmi_init(test,
 						     BIT(HDMI_COLORSPACE_RGB),
 						     10);
 	KUNIT_ASSERT_NOT_NULL(test, priv);
 
+	conn = &priv->connector;
+	ret = set_connector_edid(test, conn,
+				 test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz,
+				 ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz));
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	ctx = drm_kunit_helper_acquire_ctx_alloc(test);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
 
-	conn = &priv->connector;
 	preferred = find_preferred_mode(conn);
 	KUNIT_ASSERT_NOT_NULL(test, preferred);
 
 	drm = &priv->drm;
 	crtc = priv->crtc;
@@ -670,11 +677,11 @@  static void drm_test_check_format_value(struct kunit *test)
 						     8);
 	KUNIT_ASSERT_NOT_NULL(test, priv);
 
 	conn = &priv->connector;
 	conn_state = conn->state;
-	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, HDMI_COLORSPACE_RGB);
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, 0);
 }
 
 /*
  * Test that the value of the output format property out of reset is set
  * to 0, and will be computed at atomic_check time.