From db9c06dfff43b2a040ba2b4f2300c30e454dd930 Mon Sep 17 00:00:00 2001 From: Johnson Lin Date: Tue, 30 Jan 2018 21:21:29 +0530 Subject: [PATCH] drm/i915: Fix Limited Range Color Handling MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Some panels support limited range output (16-235) compared to full range RGB values (0-255). Also userspace can control the RGB range using "Broadcast RGB" property. Currently the code to handle full range to limited range is broken. This patch fixes the same by properly scaling down all the full range co-efficients with limited range scaling factor. v2: Fixed Ville's review comments. v3: Changed input to const and used correct data types as suggested by Ville v4: Fixed some missing data type corrections. Signed-off-by: Johnson Lin Signed-off-by: Uma Shankar Reviewed-by: Ville Syrjälä Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/1517327489-26128-1-git-send-email-uma.shankar@intel.com --- drivers/gpu/drm/i915/intel_color.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c index aa66e95..a383d99 100644 --- a/drivers/gpu/drm/i915/intel_color.c +++ b/drivers/gpu/drm/i915/intel_color.c @@ -84,26 +84,25 @@ static bool crtc_state_is_legacy_gamma(struct drm_crtc_state *state) /* * When using limited range, multiply the matrix given by userspace by - * the matrix that we would use for the limited range. We do the - * multiplication in U2.30 format. + * the matrix that we would use for the limited range. */ -static void ctm_mult_by_limited(uint64_t *result, int64_t *input) +static void ctm_mult_by_limited(u64 *result, const u64 *input) { int i; - for (i = 0; i < 9; i++) - result[i] = 0; + for (i = 0; i < 9; i++) { + u64 user_coeff = input[i]; + u32 limited_coeff = CTM_COEFF_LIMITED_RANGE; + u32 abs_coeff = clamp_val(CTM_COEFF_ABS(user_coeff), 0, + CTM_COEFF_4_0 - 1) >> 2; - for (i = 0; i < 3; i++) { - int64_t user_coeff = input[i * 3 + i]; - uint64_t limited_coeff = CTM_COEFF_LIMITED_RANGE >> 2; - uint64_t abs_coeff = clamp_val(CTM_COEFF_ABS(user_coeff), - 0, - CTM_COEFF_4_0 - 1) >> 2; - - result[i * 3 + i] = (limited_coeff * abs_coeff) >> 27; - if (CTM_COEFF_NEGATIVE(user_coeff)) - result[i * 3 + i] |= CTM_COEFF_SIGN; + /* + * By scaling every co-efficient with limited range (16-235) + * vs full range (0-255) the final o/p will be scaled down to + * fit in the limited range supported by the panel. + */ + result[i] = mul_u32_u32(limited_coeff, abs_coeff) >> 30; + result[i] |= user_coeff & CTM_COEFF_SIGN; } } -- 2.7.4