drm: introduce pipe color correction properties

Patch based on a previous series by Shashank Sharma.

This introduces optional properties to enable color correction at the
pipe level. It relies on 3 transformations applied to every pixels
displayed. First a lookup into a degamma table, then a multiplication
of the rgb components by a 3x3 matrix and finally another lookup into
a gamma table.

The following properties can be added to a pipe :
  - DEGAMMA_LUT : blob containing degamma LUT
  - DEGAMMA_LUT_SIZE : number of elements in DEGAMMA_LUT
  - CTM : transformation matrix applied after the degamma LUT
  - GAMMA_LUT : blob containing gamma LUT
  - GAMMA_LUT_SIZE : number of elements in GAMMA_LUT

DEGAMMA_LUT_SIZE and GAMMA_LUT_SIZE are read only properties, set by
the driver to tell userspace applications what sizes should be the
lookup tables in DEGAMMA_LUT and GAMMA_LUT.

A helper is also provided so legacy gamma correction is redirected
through these new properties.

v2: Register LUT size properties as range

v3: Fix round in drm_color_lut_get_value() helper
    More docs on how degamma/gamma properties are used

v4: Update contributors

v5: Rename CTM_MATRIX property to CTM (Doh!)
    Add legacy gamma_set atomic helper
    Describe CTM/LUT acronyms in the kernel doc

v6: Fix missing blob unref in drm_atomic_helper_crtc_reset

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Kumar, Kiran S <kiran.s.kumar@intel.com>
Signed-off-by: Kausal Malladi <kausalmalladi@gmail.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Rob Bradford <robert.bradford@intel.com>
[danvet: CrOS maintainers are also happy with the userspacde side:
https://codereview.chromium.org/1182063002/ ]
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1456506302-640-4-git-send-email-lionel.g.landwerlin@intel.com

1 files changed, 57 insertions, 2 deletions

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
index fe6b36a2fd98..1692c4dd5487 100644
--- a/Documentation/DocBook/gpu.tmpl
+++ b/Documentation/DocBook/gpu.tmpl
@@ -1816,7 +1816,7 @@ void intel_crt_init(struct drm_device *dev)
 	<td valign="top" >Description/Restrictions</td>
 	</tr>
 	<tr>
-	<td rowspan="37" valign="top" >DRM</td>
+	<td rowspan="42" valign="top" >DRM</td>
 	<td valign="top" >Generic</td>
 	<td valign="top" >“rotation”</td>
 	<td valign="top" >BITMASK</td>
@@ -2068,7 +2068,7 @@ void intel_crt_init(struct drm_device *dev)
 	<td valign="top" >property to suggest an Y offset for a connector</td>
 	</tr>
 	<tr>
-	<td rowspan="3" valign="top" >Optional</td>
+	<td rowspan="8" valign="top" >Optional</td>
 	<td valign="top" >“scaling mode”</td>
 	<td valign="top" >ENUM</td>
 	<td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td>
@@ -2092,6 +2092,61 @@ void intel_crt_init(struct drm_device *dev)
 	<td valign="top" >TBD</td>
 	</tr>
 	<tr>
+	<td valign="top" >“DEGAMMA_LUT”</td>
+	<td valign="top" >BLOB</td>
+	<td valign="top" >0</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to set the degamma lookup table
+		(LUT) mapping pixel data from the framebuffer before it is
+		given to the transformation matrix. The data is an interpreted
+		as an array of struct drm_color_lut elements. Hardware might
+		choose not to use the full precision of the LUT elements nor
+		use all the elements of the LUT (for example the hardware
+		might choose to interpolate between LUT[0] and LUT[4]). </td>
+	</tr>
+	<tr>
+	<td valign="top" >“DEGAMMA_LUT_SIZE”</td>
+	<td valign="top" >RANGE | IMMUTABLE</td>
+	<td valign="top" >Min=0, Max=UINT_MAX</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to gives the size of the lookup
+		table to be set on the DEGAMMA_LUT property (the size depends
+		on the underlying hardware).</td>
+	</tr>
+	<tr>
+	<td valign="top" >“CTM”</td>
+	<td valign="top" >BLOB</td>
+	<td valign="top" >0</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to set the current
+		transformation matrix (CTM) apply to pixel data after the
+		lookup through the degamma LUT and before the lookup through
+		the gamma LUT. The data is an interpreted as a struct
+		drm_color_ctm.</td>
+	</tr>
+	<tr>
+	<td valign="top" >“GAMMA_LUT”</td>
+	<td valign="top" >BLOB</td>
+	<td valign="top" >0</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to set the gamma lookup table
+		(LUT) mapping pixel data after to the transformation matrix to
+		data sent to the connector. The data is an interpreted as an
+		array of struct drm_color_lut elements. Hardware might choose
+		not to use the full precision of the LUT elements nor use all
+		the elements of the LUT (for example the hardware might choose
+		to interpolate between LUT[0] and LUT[4]).</td>
+	</tr>
+	<tr>
+	<td valign="top" >“GAMMA_LUT_SIZE”</td>
+	<td valign="top" >RANGE | IMMUTABLE</td>
+	<td valign="top" >Min=0, Max=UINT_MAX</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to gives the size of the lookup
+		table to be set on the GAMMA_LUT property (the size depends on
+		the underlying hardware).</td>
+	</tr>
+	<tr>
 	<td rowspan="20" valign="top" >i915</td>
 	<td rowspan="2" valign="top" >Generic</td>
 	<td valign="top" >"Broadcast RGB"</td>