UPSTREAM: drm/i915: Fix Limited Range Color Handling
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.
BUG=chromium:848540, b:138612512
TEST=boot on samus-kernelnext, test all resolutions with USB-C attached
monitor to make sure colors are never washed out
Signed-off-by: Johnson Lin <johnson.lin@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjl <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjl <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1517327489-26128-1-git-send-email-uma.shankar@intel.com
(cherry picked from commit db9c06dfff43b2a040ba2b4f2300c30e454dd930)
Signed-off-by: Stphane Marchesin <marcheu@chromium.org>
Change-Id: Idd4092c779a60fb7f55fc6f8cf0ae956136e6d4d
Signed-off-by: Ross Zwisler <zwisler@google.com>
Signed-off-by: Jon Flatley <jflat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1729910
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Jon Flatley <jflat@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
(cherry picked from commit 04b5e08e2e1e8ffb90fa23dfbf43784efe23f4f1)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1738444
diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
index b8315bc..9e79a7e 100644
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -84,26 +84,25 @@
/*
* 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;
}
}
