diff mbox series

[1/2] drm: Add color management LUT validation helpers

Message ID 20181212010551.6337-2-matthew.d.roper@intel.com (mailing list archive)
State New, archived
Headers show
Series Add gamma/degamma LUT validation helpers | expand

Commit Message

Matt Roper Dec. 12, 2018, 1:05 a.m. UTC 
Some hardware may place additional restrictions on the gamma/degamma
curves described by our LUT properties.  E.g., that a gamma curve never
decreases or that the red/green/blue channels of a LUT's entries must be
equal.  Let's add a couple helpers that drivers can use to test that a
userspace-provided LUT doesn't violate hardware requirements.

Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Swati Sharma <swati2.sharma@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
 drivers/gpu/drm/drm_color_mgmt.c | 53 ++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_color_mgmt.h     |  3 +++
 2 files changed, 56 insertions(+)

Comments

Brian Starkey Dec. 12, 2018, 9:56 a.m. UTC | #1 
Hi Matt,

On Tue, Dec 11, 2018 at 05:05:50PM -0800, Matt Roper wrote:
> Some hardware may place additional restrictions on the gamma/degamma
> curves described by our LUT properties.  E.g., that a gamma curve never
> decreases or that the red/green/blue channels of a LUT's entries must be
> equal.  Let's add a couple helpers that drivers can use to test that a
> userspace-provided LUT doesn't violate hardware requirements.
> 
> Cc: Uma Shankar <uma.shankar@intel.com>
> Cc: Swati Sharma <swati2.sharma@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  drivers/gpu/drm/drm_color_mgmt.c | 53 ++++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_color_mgmt.h     |  3 +++
>  2 files changed, 56 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
> index 07dcf47daafe..41e617e34c10 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -462,3 +462,56 @@ int drm_plane_create_color_properties(struct drm_plane *plane,
>  	return 0;
>  }
>  EXPORT_SYMBOL(drm_plane_create_color_properties);
> +
> +/**
> + * drm_color_lut_has_equal_channels - check LUT for equal r/g/b values
> + * @lut: property blob containing LUT to check
> + *
> + * Helper to check whether the entries of a LUT all have equal values for the
> + * red, green, and blue channels.  Some hardware can only be programmed
> + * with a single value per LUT entry, which is assumed to apply to all
> + * three color components.
> + */
> +bool drm_color_lut_has_equal_channels(struct drm_property_blob *lut)
> +{
> +	struct drm_color_lut *entry;
> +	int i;
> +
> +	if (!lut)
> +		return true;
> +
> +	entry = lut->data;
> +	for (i = 0; i < drm_color_lut_size(lut); i++)
> +		if (entry[i].red != entry[i].blue ||
> +		    entry[i].red != entry[i].green)
> +			return false;
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(drm_color_lut_has_equal_channels);

We've got this open-coded for some of our HW, so thanks for the helper
:-)

> +
> +/**
> + * drm_color_lut_is_increasing - check that LUT is always flat/increasing
> + * @lut: LUT to check
> + *
> + * Helper to check whether the entries of a LUT are always flat or increasing
> + * (never decreasing).
> + */
> +bool drm_color_lut_is_increasing(struct drm_property_blob *lut)
> +{
> +	struct drm_color_lut *entry;
> +	int i;
> +
> +	if (!lut)
> +		return true;
> +
> +	entry = lut->data;
> +	for (i = 1; i < drm_color_lut_size(lut); i++)
> +		if (entry[i].red < entry[i-1].red ||
> +		    entry[i].green < entry[i-1].green ||
> +		    entry[i].blue < entry[i-1].blue)
> +			return false;

nit: I think checkpatch likes spaces around operators: [i - 1]

Another thought: in the worst case with a valid LUT with HW that needs
both checks, you can end up iterating the whole LUT twice - once for
increasing, and once for equal channels.

Maybe this could be a single function with a mask of constraints to
check:

  drm_color_lut_check(lut, DRM_COLOR_LUT_EQUAL_CHANNELS | DRM_COLOR_LUT_INCREASING);

Not sure if it would turn out messy with the different loop bounds.

Either way, for mali-dp it makes no difference, and probably
LUTs aren't changing all the time so:

Reviewed-by: Brian Starkey <brian.starkey@arm.com>

> +
> +	return true;
> +}
> +EXPORT_SYMBOL(drm_color_lut_is_increasing);
> diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
> index 90ef9996d9a4..6c38f5477e29 100644
> --- a/include/drm/drm_color_mgmt.h
> +++ b/include/drm/drm_color_mgmt.h
> @@ -69,4 +69,7 @@ int drm_plane_create_color_properties(struct drm_plane *plane,
>  				      u32 supported_ranges,
>  				      enum drm_color_encoding default_encoding,
>  				      enum drm_color_range default_range);
> +
> +bool drm_color_lut_has_equal_channels(struct drm_property_blob *lut);
> +bool drm_color_lut_is_increasing(struct drm_property_blob *lut);
>  #endif
> -- 
> 2.14.4
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index 07dcf47daafe..41e617e34c10 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -462,3 +462,56 @@  int drm_plane_create_color_properties(struct drm_plane *plane,
 	return 0;
 }
 EXPORT_SYMBOL(drm_plane_create_color_properties);
+
+/**
+ * drm_color_lut_has_equal_channels - check LUT for equal r/g/b values
+ * @lut: property blob containing LUT to check
+ *
+ * Helper to check whether the entries of a LUT all have equal values for the
+ * red, green, and blue channels.  Some hardware can only be programmed
+ * with a single value per LUT entry, which is assumed to apply to all
+ * three color components.
+ */
+bool drm_color_lut_has_equal_channels(struct drm_property_blob *lut)
+{
+	struct drm_color_lut *entry;
+	int i;
+
+	if (!lut)
+		return true;
+
+	entry = lut->data;
+	for (i = 0; i < drm_color_lut_size(lut); i++)
+		if (entry[i].red != entry[i].blue ||
+		    entry[i].red != entry[i].green)
+			return false;
+
+	return true;
+}
+EXPORT_SYMBOL(drm_color_lut_has_equal_channels);
+
+/**
+ * drm_color_lut_is_increasing - check that LUT is always flat/increasing
+ * @lut: LUT to check
+ *
+ * Helper to check whether the entries of a LUT are always flat or increasing
+ * (never decreasing).
+ */
+bool drm_color_lut_is_increasing(struct drm_property_blob *lut)
+{
+	struct drm_color_lut *entry;
+	int i;
+
+	if (!lut)
+		return true;
+
+	entry = lut->data;
+	for (i = 1; i < drm_color_lut_size(lut); i++)
+		if (entry[i].red < entry[i-1].red ||
+		    entry[i].green < entry[i-1].green ||
+		    entry[i].blue < entry[i-1].blue)
+			return false;
+
+	return true;
+}
+EXPORT_SYMBOL(drm_color_lut_is_increasing);
diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
index 90ef9996d9a4..6c38f5477e29 100644
--- a/include/drm/drm_color_mgmt.h
+++ b/include/drm/drm_color_mgmt.h
@@ -69,4 +69,7 @@  int drm_plane_create_color_properties(struct drm_plane *plane,
 				      u32 supported_ranges,
 				      enum drm_color_encoding default_encoding,
 				      enum drm_color_range default_range);
+
+bool drm_color_lut_has_equal_channels(struct drm_property_blob *lut);
+bool drm_color_lut_is_increasing(struct drm_property_blob *lut);
 #endif