On Thu, 2019-07-18 at 17:50 +0300, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
Add comments to explain the ilk pipe csc operation a bit better.
Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
drivers/gpu/drm/i915/display/intel_color.c | 26 +++++++++++++++++---
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c index 23a84dd7989f..736c42720daf 100644 --- a/drivers/gpu/drm/i915/display/intel_color.c +++ b/drivers/gpu/drm/i915/display/intel_color.c @@ -42,6 +42,21 @@
#define LEGACY_LUT_LENGTH 256
+/*
- ILK+ csc matrix:
- |R/Cr| | c0 c1 c2 | ( |R/Cr| |preoff0| ) |postoff0|
- |G/Y | = | c3 c4 c5 | x ( |G/Y | + |preoff1| ) + |postoff1|
- |B/Cb| | c6 c7 c8 | ( |B/Cb| |preoff2| ) |postoff2|
- ILK/SNB don't have explicit post offsets, and instead
- CSC_MODE_YUV_TO_RGB and CSC_BLACK_SCREEN_OFFSET are used:
- CSC_MODE_YUV_TO_RGB=0 + CSC_BLACK_SCREEN_OFFSET=0 -> 1/2, 0, 1/2
- CSC_MODE_YUV_TO_RGB=0 + CSC_BLACK_SCREEN_OFFSET=1 -> 1/2, 1/16,
1/2
It seems that the calculated values are assumes ITU-R BT.709 spec, if you don't mind, can we add some comments which is based on ITU-R BT.709?
- CSC_MODE_YUV_TO_RGB=1 + CSC_BLACK_SCREEN_OFFSET=0 -> 0, 0, 0
- CSC_MODE_YUV_TO_RGB=1 + CSC_BLACK_SCREEN_OFFSET=1 -> 1/16, 1/16,
1/16
- */
/*
- Extract the CSC coefficient from a CTM coefficient (in U32.32
fixed point
- format). This macro takes the coefficient we want transformed and
the @@ -59,37 +74,38 @@
#define ILK_CSC_POSTOFF_LIMITED_RANGE (16 * (1 << 12) / 255)
+/* Nop pre/post offsets */ static const u16 ilk_csc_off_zero[3] = {};
+/* Identity matrix */ static const u16 ilk_csc_coeff_identity[9] = { ILK_CSC_COEFF_1_0, 0, 0, 0, ILK_CSC_COEFF_1_0, 0, 0, 0, ILK_CSC_COEFF_1_0, };
+/* Limited range RGB post offsets */ static const u16 ilk_csc_postoff_limited_range[3] = { ILK_CSC_POSTOFF_LIMITED_RANGE, ILK_CSC_POSTOFF_LIMITED_RANGE, ILK_CSC_POSTOFF_LIMITED_RANGE, };
+/* Full range RGB -> limited range RGB matrix */ static const u16 ilk_csc_coeff_limited_range[9] = { ILK_CSC_COEFF_LIMITED_RANGE, 0, 0, 0, ILK_CSC_COEFF_LIMITED_RANGE, 0, 0, 0, ILK_CSC_COEFF_LIMITED_RANGE, };
-/*
- These values are direct register values specified in the Bspec,
- for RGB->YUV conversion matrix (colorspace BT709)
- */
+/* BT.709 full range RGB -> limited range YCbCr matrix */ static const u16 ilk_csc_coeff_rgb_to_ycbcr[9] = { 0x1e08, 0x9cc0, 0xb528, 0x2ba8, 0x09d8, 0x37e8, 0xbce8, 0x9ad8, 0x1e08, };
-/* Post offset values for RGB->YCBCR conversion */ +/* Limited range YCbCr post offsets */ static const u16 ilk_csc_postoff_rgb_to_ycbcr[3] = { 0x0800, 0x0100, 0x0800, };
The changes look good to me. Reviewed-by: Gwan-gyeong Mun gwan-gyeong.mun@intel.com