From 174d12bcc0874d78ad7fd63ae769cac864ee9f4f Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Thu, 18 Jul 2019 17:50:51 +0300 Subject: [PATCH] drm/i915: Document ILK+ pipe csc matrix better MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add comments to explain the ilk pipe csc operation a bit better. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20190718145053.25808-11-ville.syrjala@linux.intel.com Reviewed-by: Gwan-gyeong Mun --- 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 318308d..de31b4c 100644 --- a/drivers/gpu/drm/i915/display/intel_color.c +++ b/drivers/gpu/drm/i915/display/intel_color.c @@ -43,6 +43,21 @@ #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 + * 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 * number of fractional bits. @@ -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, }; -- 2.7.4