[2/5] drm/edid: Introduce drm_default_rgb_quant_range()

Commit Message

Ville Syrjala Jan. 11, 2017, 12:57 p.m. UTC

From: Ville Syrjälä <[e-mail]>

Make the code selecting the RGB quantization range a little less magicy
by wrapping it up in a small helper.

Signed-off-by: Ville Syrjälä <[e-mail]>
---
 drivers/gpu/drm/drm_edid.c        | 18 ++++++++++++++++++
 drivers/gpu/drm/i915/intel_dp.c   |  4 +++-
 drivers/gpu/drm/i915/intel_hdmi.c |  3 ++-
 drivers/gpu/drm/vc4/vc4_hdmi.c    |  4 +++-
 include/drm/drm_edid.h            |  2 ++
 5 files changed, 28 insertions(+), 3 deletions(-)

Comments

Daniel Vetter Jan. 11, 2017, 4:16 p.m. UTC | #1

On Wed, Jan 11, 2017 at 02:57:22PM +0200, [e-mail] wrote:
> From: Ville Syrjälä <[e-mail]>
> 
> Make the code selecting the RGB quantization range a little less magicy
> by wrapping it up in a small helper.
> 
> Signed-off-by: Ville Syrjälä <[e-mail]>

Needs cc: for driver maintainers, Eric for vc4 here.
-Daniel

> ---
>  drivers/gpu/drm/drm_edid.c        | 18 ++++++++++++++++++
>  drivers/gpu/drm/i915/intel_dp.c   |  4 +++-
>  drivers/gpu/drm/i915/intel_hdmi.c |  3 ++-
>  drivers/gpu/drm/vc4/vc4_hdmi.c    |  4 +++-
>  include/drm/drm_edid.h            |  2 ++
>  5 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 4ff04aa84dd0..304c583b8000 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3768,6 +3768,24 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
>  }
>  EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
>  
> +/**
> + * drm_default_rgb_quant_range - default RGB quantization range
> + * @mode: display mode
> + *
> + * Determine the default RGB quantization range for the mode,
> + * as specified in CEA-861.
> + *
> + * Return: The default RGB quantization range for the mode
> + */
> +enum hdmi_quantization_range
> +drm_default_rgb_quant_range(const struct drm_display_mode *mode)
> +{
> +	return drm_match_cea_mode(mode) > 1 ?
> +		HDMI_QUANTIZATION_RANGE_LIMITED :
> +		HDMI_QUANTIZATION_RANGE_FULL;
> +}
> +EXPORT_SYMBOL(drm_default_rgb_quant_range);
> +
>  static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>  					   const u8 *hdmi)
>  {
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 343e1d9fa761..d4befbbe834a 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1713,7 +1713,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
>  		 * VESA DisplayPort Ver.1.2a - 5.1.1.1 Video Colorimetry
>  		 */
>  		pipe_config->limited_color_range =
> -			bpp != 18 && drm_match_cea_mode(adjusted_mode) > 1;
> +			bpp != 18 &&
> +			drm_default_rgb_quant_range(adjusted_mode) ==
> +			HDMI_QUANTIZATION_RANGE_LIMITED;
>  	} else {
>  		pipe_config->limited_color_range =
>  			intel_dp->limited_color_range;
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 0bcfead14571..19bd13f53729 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1330,7 +1330,8 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
>  		/* See CEA-861-E - 5.1 Default Encoding Parameters */
>  		pipe_config->limited_color_range =
>  			pipe_config->has_hdmi_sink &&
> -			drm_match_cea_mode(adjusted_mode) > 1;
> +			drm_default_rgb_quant_range(adjusted_mode) ==
> +			HDMI_QUANTIZATION_RANGE_LIMITED;
>  	} else {
>  		pipe_config->limited_color_range =
>  			intel_hdmi->limited_color_range;
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index c4cb2e26de32..d79466a42690 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -463,7 +463,9 @@ static void vc4_hdmi_encoder_mode_set(struct drm_encoder *encoder,
>  	csc_ctl = VC4_SET_FIELD(VC4_HD_CSC_CTL_ORDER_BGR,
>  				VC4_HD_CSC_CTL_ORDER);
>  
> -	if (vc4_encoder->hdmi_monitor && drm_match_cea_mode(mode) > 1) {
> +	if (vc4_encoder->hdmi_monitor &&
> +	    drm_default_rgb_quant_range(adjusted_mode) ==
> +	    HDMI_QUANTIZATION_RANGE_LIMITED) {
>  		/* CEA VICs other than #1 requre limited range RGB
>  		 * output unless overridden by an AVI infoframe.
>  		 * Apply a colorspace conversion to squash 0-255 down
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 838eaf2b42e9..25cdf5f7a0d8 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -441,6 +441,8 @@ enum hdmi_picture_aspect drm_get_cea_aspect_ratio(const u8 video_code);
>  bool drm_detect_hdmi_monitor(struct edid *edid);
>  bool drm_detect_monitor_audio(struct edid *edid);
>  bool drm_rgb_quant_range_selectable(struct edid *edid);
> +enum hdmi_quantization_range
> +drm_default_rgb_quant_range(const struct drm_display_mode *mode);
>  int drm_add_modes_noedid(struct drm_connector *connector,
>  			 int hdisplay, int vdisplay);
>  void drm_set_preferred_mode(struct drm_connector *connector,
> -- 
> 2.10.2
> 
> _______________________________________________
> Intel-gfx mailing list
> [e-mail]
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Ville Syrjala Jan. 11, 2017, 4:31 p.m. UTC | #2

On Wed, Jan 11, 2017 at 05:16:54PM +0100, Daniel Vetter wrote:
> On Wed, Jan 11, 2017 at 02:57:22PM +0200, [e-mail] wrote:
> > From: Ville Syrjälä <[e-mail]>
> > 
> > Make the code selecting the RGB quantization range a little less magicy
> > by wrapping it up in a small helper.
> > 
> > Signed-off-by: Ville Syrjälä <[e-mail]>
> 
> Needs cc: for driver maintainers, Eric for vc4 here.

Eric was cc:d. I was just too lazy to add the cc:s to all the commit
messages, and so i just used --cc on the whole lot.

> -Daniel
> 
> > ---
> >  drivers/gpu/drm/drm_edid.c        | 18 ++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_dp.c   |  4 +++-
> >  drivers/gpu/drm/i915/intel_hdmi.c |  3 ++-
> >  drivers/gpu/drm/vc4/vc4_hdmi.c    |  4 +++-
> >  include/drm/drm_edid.h            |  2 ++
> >  5 files changed, 28 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 4ff04aa84dd0..304c583b8000 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -3768,6 +3768,24 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
> >  }
> >  EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
> >  
> > +/**
> > + * drm_default_rgb_quant_range - default RGB quantization range
> > + * @mode: display mode
> > + *
> > + * Determine the default RGB quantization range for the mode,
> > + * as specified in CEA-861.
> > + *
> > + * Return: The default RGB quantization range for the mode
> > + */
> > +enum hdmi_quantization_range
> > +drm_default_rgb_quant_range(const struct drm_display_mode *mode)
> > +{
> > +	return drm_match_cea_mode(mode) > 1 ?
> > +		HDMI_QUANTIZATION_RANGE_LIMITED :
> > +		HDMI_QUANTIZATION_RANGE_FULL;
> > +}
> > +EXPORT_SYMBOL(drm_default_rgb_quant_range);
> > +
> >  static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
> >  					   const u8 *hdmi)
> >  {
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 343e1d9fa761..d4befbbe834a 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -1713,7 +1713,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> >  		 * VESA DisplayPort Ver.1.2a - 5.1.1.1 Video Colorimetry
> >  		 */
> >  		pipe_config->limited_color_range =
> > -			bpp != 18 && drm_match_cea_mode(adjusted_mode) > 1;
> > +			bpp != 18 &&
> > +			drm_default_rgb_quant_range(adjusted_mode) ==
> > +			HDMI_QUANTIZATION_RANGE_LIMITED;
> >  	} else {
> >  		pipe_config->limited_color_range =
> >  			intel_dp->limited_color_range;
> > diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> > index 0bcfead14571..19bd13f53729 100644
> > --- a/drivers/gpu/drm/i915/intel_hdmi.c
> > +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> > @@ -1330,7 +1330,8 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
> >  		/* See CEA-861-E - 5.1 Default Encoding Parameters */
> >  		pipe_config->limited_color_range =
> >  			pipe_config->has_hdmi_sink &&
> > -			drm_match_cea_mode(adjusted_mode) > 1;
> > +			drm_default_rgb_quant_range(adjusted_mode) ==
> > +			HDMI_QUANTIZATION_RANGE_LIMITED;
> >  	} else {
> >  		pipe_config->limited_color_range =
> >  			intel_hdmi->limited_color_range;
> > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > index c4cb2e26de32..d79466a42690 100644
> > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > @@ -463,7 +463,9 @@ static void vc4_hdmi_encoder_mode_set(struct drm_encoder *encoder,
> >  	csc_ctl = VC4_SET_FIELD(VC4_HD_CSC_CTL_ORDER_BGR,
> >  				VC4_HD_CSC_CTL_ORDER);
> >  
> > -	if (vc4_encoder->hdmi_monitor && drm_match_cea_mode(mode) > 1) {
> > +	if (vc4_encoder->hdmi_monitor &&
> > +	    drm_default_rgb_quant_range(adjusted_mode) ==
> > +	    HDMI_QUANTIZATION_RANGE_LIMITED) {
> >  		/* CEA VICs other than #1 requre limited range RGB
> >  		 * output unless overridden by an AVI infoframe.
> >  		 * Apply a colorspace conversion to squash 0-255 down
> > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> > index 838eaf2b42e9..25cdf5f7a0d8 100644
> > --- a/include/drm/drm_edid.h
> > +++ b/include/drm/drm_edid.h
> > @@ -441,6 +441,8 @@ enum hdmi_picture_aspect drm_get_cea_aspect_ratio(const u8 video_code);
> >  bool drm_detect_hdmi_monitor(struct edid *edid);
> >  bool drm_detect_monitor_audio(struct edid *edid);
> >  bool drm_rgb_quant_range_selectable(struct edid *edid);
> > +enum hdmi_quantization_range
> > +drm_default_rgb_quant_range(const struct drm_display_mode *mode);
> >  int drm_add_modes_noedid(struct drm_connector *connector,
> >  			 int hdisplay, int vdisplay);
> >  void drm_set_preferred_mode(struct drm_connector *connector,
> > -- 
> > 2.10.2
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > [e-mail]
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

Daniel Vetter Jan. 12, 2017, 8 a.m. UTC | #3

On Wed, Jan 11, 2017 at 06:31:52PM +0200, Ville Syrjälä wrote:
> On Wed, Jan 11, 2017 at 05:16:54PM +0100, Daniel Vetter wrote:
> > On Wed, Jan 11, 2017 at 02:57:22PM +0200, [e-mail] wrote:
> > > From: Ville Syrjälä <[e-mail]>
> > > 
> > > Make the code selecting the RGB quantization range a little less magicy
> > > by wrapping it up in a small helper.
> > > 
> > > Signed-off-by: Ville Syrjälä <[e-mail]>
> > 
> > Needs cc: for driver maintainers, Eric for vc4 here.
> 
> Eric was cc:d. I was just too lazy to add the cc:s to all the commit
> messages, and so i just used --cc on the whole lot.

Hm, he's not on the cc: list over here (on the mails, not in the patch
body).
-Daniel

Michel Dänzer Jan. 12, 2017, 8:13 a.m. UTC | #4

On 12/01/17 05:00 PM, Daniel Vetter wrote:
> On Wed, Jan 11, 2017 at 06:31:52PM +0200, Ville Syrjälä wrote:
>> On Wed, Jan 11, 2017 at 05:16:54PM +0100, Daniel Vetter wrote:
>>> On Wed, Jan 11, 2017 at 02:57:22PM +0200, [e-mail] wrote:
>>>> From: Ville Syrjälä <[e-mail]>
>>>>
>>>> Make the code selecting the RGB quantization range a little less magicy
>>>> by wrapping it up in a small helper.
>>>>
>>>> Signed-off-by: Ville Syrjälä <[e-mail]>
>>>
>>> Needs cc: for driver maintainers, Eric for vc4 here.
>>
>> Eric was cc:d. I was just too lazy to add the cc:s to all the commit
>> messages, and so i just used --cc on the whole lot.
> 
> Hm, he's not on the cc: list over here (on the mails, not in the patch
> body).

That could be because he has "Avoid duplicate copies of messages?"
enabled in his mailman subscription options.

Eric Anholt Jan. 20, 2017, 7:50 p.m. UTC | #5

[e-mail] writes:

> From: Ville Syrjälä <[e-mail]>
>
> Make the code selecting the RGB quantization range a little less magicy
> by wrapping it up in a small helper.

This series seems good.  I won't have the ability to test it on vc4
within a reasonable time frame, so you can add an Acked-by from me if
you'd like.  Just one comment that you can take or leave:

> Signed-off-by: Ville Syrjälä <[e-mail]>
> ---
>  drivers/gpu/drm/drm_edid.c        | 18 ++++++++++++++++++
>  drivers/gpu/drm/i915/intel_dp.c   |  4 +++-
>  drivers/gpu/drm/i915/intel_hdmi.c |  3 ++-
>  drivers/gpu/drm/vc4/vc4_hdmi.c    |  4 +++-
>  include/drm/drm_edid.h            |  2 ++
>  5 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 4ff04aa84dd0..304c583b8000 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3768,6 +3768,24 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
>  }
>  EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
>  
> +/**
> + * drm_default_rgb_quant_range - default RGB quantization range
> + * @mode: display mode
> + *
> + * Determine the default RGB quantization range for the mode,
> + * as specified in CEA-861.
> + *
> + * Return: The default RGB quantization range for the mode
> + */
> +enum hdmi_quantization_range
> +drm_default_rgb_quant_range(const struct drm_display_mode *mode)
> +{
> +	return drm_match_cea_mode(mode) > 1 ?
> +		HDMI_QUANTIZATION_RANGE_LIMITED :
> +		HDMI_QUANTIZATION_RANGE_FULL;

It might be nice to add a comment here like

/* All CEA modes other than VIC 1 use limited quantization range. */

When I first had to put this logic in vc4, I was surprised by it and
figured that it was an off-by-one bug in code that was trying to say "if
it's any CEA mode then it should be limited range"


> +}
> +EXPORT_SYMBOL(drm_default_rgb_quant_range);

Ville Syrjala Jan. 20, 2017, 8 p.m. UTC | #6

On Sat, Jan 21, 2017 at 06:50:57AM +1100, Eric Anholt wrote:
> [e-mail] writes:
> 
> > From: Ville Syrjälä <[e-mail]>
> >
> > Make the code selecting the RGB quantization range a little less magicy
> > by wrapping it up in a small helper.
> 
> This series seems good.  I won't have the ability to test it on vc4
> within a reasonable time frame, so you can add an Acked-by from me if
> you'd like.  Just one comment that you can take or leave:
> 
> > Signed-off-by: Ville Syrjälä <[e-mail]>
> > ---
> >  drivers/gpu/drm/drm_edid.c        | 18 ++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_dp.c   |  4 +++-
> >  drivers/gpu/drm/i915/intel_hdmi.c |  3 ++-
> >  drivers/gpu/drm/vc4/vc4_hdmi.c    |  4 +++-
> >  include/drm/drm_edid.h            |  2 ++
> >  5 files changed, 28 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 4ff04aa84dd0..304c583b8000 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -3768,6 +3768,24 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
> >  }
> >  EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
> >  
> > +/**
> > + * drm_default_rgb_quant_range - default RGB quantization range
> > + * @mode: display mode
> > + *
> > + * Determine the default RGB quantization range for the mode,
> > + * as specified in CEA-861.
> > + *
> > + * Return: The default RGB quantization range for the mode
> > + */
> > +enum hdmi_quantization_range
> > +drm_default_rgb_quant_range(const struct drm_display_mode *mode)
> > +{
> > +	return drm_match_cea_mode(mode) > 1 ?
> > +		HDMI_QUANTIZATION_RANGE_LIMITED :
> > +		HDMI_QUANTIZATION_RANGE_FULL;
> 
> It might be nice to add a comment here like
> 
> /* All CEA modes other than VIC 1 use limited quantization range. */
> 
> When I first had to put this logic in vc4, I was surprised by it and
> figured that it was an off-by-one bug in code that was trying to say "if
> it's any CEA mode then it should be limited range"

Seems like a good idea. I could even try to dig up a specific spec
quote perhaps? And if I can't find anything succinct in the spec we
can always go with your proposal.

> 
> 
> > +}
> > +EXPORT_SYMBOL(drm_default_rgb_quant_range);

Ville Syrjala Jan. 20, 2017, 8:37 p.m. UTC | #7

On Fri, Jan 20, 2017 at 10:00:34PM +0200, Ville Syrjälä wrote:
> On Sat, Jan 21, 2017 at 06:50:57AM +1100, Eric Anholt wrote:
> > [e-mail] writes:
> > 
> > > From: Ville Syrjälä <[e-mail]>
> > >
> > > Make the code selecting the RGB quantization range a little less magicy
> > > by wrapping it up in a small helper.
> > 
> > This series seems good.  I won't have the ability to test it on vc4
> > within a reasonable time frame, so you can add an Acked-by from me if
> > you'd like.  Just one comment that you can take or leave:
> > 
> > > Signed-off-by: Ville Syrjälä <[e-mail]>
> > > ---
> > >  drivers/gpu/drm/drm_edid.c        | 18 ++++++++++++++++++
> > >  drivers/gpu/drm/i915/intel_dp.c   |  4 +++-
> > >  drivers/gpu/drm/i915/intel_hdmi.c |  3 ++-
> > >  drivers/gpu/drm/vc4/vc4_hdmi.c    |  4 +++-
> > >  include/drm/drm_edid.h            |  2 ++
> > >  5 files changed, 28 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > > index 4ff04aa84dd0..304c583b8000 100644
> > > --- a/drivers/gpu/drm/drm_edid.c
> > > +++ b/drivers/gpu/drm/drm_edid.c
> > > @@ -3768,6 +3768,24 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
> > >  }
> > >  EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
> > >  
> > > +/**
> > > + * drm_default_rgb_quant_range - default RGB quantization range
> > > + * @mode: display mode
> > > + *
> > > + * Determine the default RGB quantization range for the mode,
> > > + * as specified in CEA-861.
> > > + *
> > > + * Return: The default RGB quantization range for the mode
> > > + */
> > > +enum hdmi_quantization_range
> > > +drm_default_rgb_quant_range(const struct drm_display_mode *mode)
> > > +{
> > > +	return drm_match_cea_mode(mode) > 1 ?
> > > +		HDMI_QUANTIZATION_RANGE_LIMITED :
> > > +		HDMI_QUANTIZATION_RANGE_FULL;
> > 
> > It might be nice to add a comment here like
> > 
> > /* All CEA modes other than VIC 1 use limited quantization range. */
> > 
> > When I first had to put this logic in vc4, I was surprised by it and
> > figured that it was an off-by-one bug in code that was trying to say "if
> > it's any CEA mode then it should be limited range"
> 
> Seems like a good idea. I could even try to dig up a specific spec
> quote perhaps? And if I can't find anything succinct in the spec we
> can always go with your proposal.

Meh. Didn't manage to dig up anything really nice from the spec, so
I'll just go with your idea.

> 
> > 
> > 
> > > +}
> > > +EXPORT_SYMBOL(drm_default_rgb_quant_range);
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> [e-mail]
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

Patch

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 4ff04aa84dd0..304c583b8000 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3768,6 +3768,24 @@  bool drm_rgb_quant_range_selectable(struct edid *edid)
 }
 EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
 
+/**
+ * drm_default_rgb_quant_range - default RGB quantization range
+ * @mode: display mode
+ *
+ * Determine the default RGB quantization range for the mode,
+ * as specified in CEA-861.
+ *
+ * Return: The default RGB quantization range for the mode
+ */
+enum hdmi_quantization_range
+drm_default_rgb_quant_range(const struct drm_display_mode *mode)
+{
+	return drm_match_cea_mode(mode) > 1 ?
+		HDMI_QUANTIZATION_RANGE_LIMITED :
+		HDMI_QUANTIZATION_RANGE_FULL;
+}
+EXPORT_SYMBOL(drm_default_rgb_quant_range);
+
 static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
 					   const u8 *hdmi)
 {
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 343e1d9fa761..d4befbbe834a 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1713,7 +1713,9 @@  intel_dp_compute_config(struct intel_encoder *encoder,
 		 * VESA DisplayPort Ver.1.2a - 5.1.1.1 Video Colorimetry
 		 */
 		pipe_config->limited_color_range =
-			bpp != 18 && drm_match_cea_mode(adjusted_mode) > 1;
+			bpp != 18 &&
+			drm_default_rgb_quant_range(adjusted_mode) ==
+			HDMI_QUANTIZATION_RANGE_LIMITED;
 	} else {
 		pipe_config->limited_color_range =
 			intel_dp->limited_color_range;
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 0bcfead14571..19bd13f53729 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1330,7 +1330,8 @@  bool intel_hdmi_compute_config(struct intel_encoder *encoder,
 		/* See CEA-861-E - 5.1 Default Encoding Parameters */
 		pipe_config->limited_color_range =
 			pipe_config->has_hdmi_sink &&
-			drm_match_cea_mode(adjusted_mode) > 1;
+			drm_default_rgb_quant_range(adjusted_mode) ==
+			HDMI_QUANTIZATION_RANGE_LIMITED;
 	} else {
 		pipe_config->limited_color_range =
 			intel_hdmi->limited_color_range;
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index c4cb2e26de32..d79466a42690 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -463,7 +463,9 @@  static void vc4_hdmi_encoder_mode_set(struct drm_encoder *encoder,
 	csc_ctl = VC4_SET_FIELD(VC4_HD_CSC_CTL_ORDER_BGR,
 				VC4_HD_CSC_CTL_ORDER);
 
-	if (vc4_encoder->hdmi_monitor && drm_match_cea_mode(mode) > 1) {
+	if (vc4_encoder->hdmi_monitor &&
+	    drm_default_rgb_quant_range(adjusted_mode) ==
+	    HDMI_QUANTIZATION_RANGE_LIMITED) {
 		/* CEA VICs other than #1 requre limited range RGB
 		 * output unless overridden by an AVI infoframe.
 		 * Apply a colorspace conversion to squash 0-255 down
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 838eaf2b42e9..25cdf5f7a0d8 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -441,6 +441,8 @@  enum hdmi_picture_aspect drm_get_cea_aspect_ratio(const u8 video_code);
 bool drm_detect_hdmi_monitor(struct edid *edid);
 bool drm_detect_monitor_audio(struct edid *edid);
 bool drm_rgb_quant_range_selectable(struct edid *edid);
+enum hdmi_quantization_range
+drm_default_rgb_quant_range(const struct drm_display_mode *mode);
 int drm_add_modes_noedid(struct drm_connector *connector,
 			 int hdisplay, int vdisplay);
 void drm_set_preferred_mode(struct drm_connector *connector,