From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
The current implementation of change_lut_val_precision() is just
a convoluted way of shifting by 8. Implement the proper rounding
by just using drm_color_lut_extract() and intel_color_lut_pack()
like everyone else does.
And as the uapi can't handle >=1.0 values but the hardware
can we need to clamp the results appropriately in the readout
path.
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_color.c | 54 +++++++++++-----------
1 file changed, 28 insertions(+), 26 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
index a4b30614bd63..1cfbb3650304 100644
--- a/drivers/gpu/drm/i915/display/intel_color.c
+++ b/drivers/gpu/drm/i915/display/intel_color.c
@@ -1526,14 +1526,27 @@ static int glk_degamma_lut_size(struct drm_i915_private *i915)
return 35;
}
-/*
- * change_lut_val_precision: helper function to upscale or downscale lut values.
- * Parameters 'to' and 'from' needs to be less than 32. This should be sufficient
- * as currently there are no lut values exceeding 32 bit.
- */
-static u32 change_lut_val_precision(u32 lut_val, int to, int from)
+static u32 glk_degamma_lut(const struct drm_color_lut *color)
+{
+ return color->green;
+}
+
+static void glk_degamma_lut_pack(struct drm_color_lut *entry, u32 val)
+{
+ /* PRE_CSC_GAMC_DATA is 3.16, clamp to 0.16 */
+ entry->red = entry->green = entry->blue = min(val, 0xffffu);
+}
+
+static u32 mtl_degamma_lut(const struct drm_color_lut *color)
+{
+ return drm_color_lut_extract(color->green, 24);
+}
+
+static void mtl_degamma_lut_pack(struct drm_color_lut *entry, u32 val)
{
- return mul_u32_u32(lut_val, (1 << to)) / (1 << from);
+ /* PRE_CSC_GAMC_DATA is 3.24, clamp to 0.16 */
+ entry->red = entry->green = entry->blue =
+ intel_color_lut_pack(min(val, 0xffffffu), 24);
}
static void glk_load_degamma_lut(const struct intel_crtc_state *crtc_state,
@@ -1570,20 +1583,16 @@ static void glk_load_degamma_lut(const struct intel_crtc_state *crtc_state,
* ToDo: Extend to max 7.0. Enable 32 bit input value
* as compared to just 16 to achieve this.
*/
- u32 lut_val;
-
- if (DISPLAY_VER(i915) >= 14)
- lut_val = change_lut_val_precision(lut[i].green, 24, 16);
- else
- lut_val = lut[i].green;
-
ilk_lut_write(crtc_state, PRE_CSC_GAMC_DATA(pipe),
- lut_val);
+ DISPLAY_VER(i915) >= 14 ?
+ mtl_degamma_lut(&lut[i]) : glk_degamma_lut(&lut[i]));
}
/* Clamp values > 1.0. */
while (i++ < glk_degamma_lut_size(i915))
- ilk_lut_write(crtc_state, PRE_CSC_GAMC_DATA(pipe), 1 << 16);
+ ilk_lut_write(crtc_state, PRE_CSC_GAMC_DATA(pipe),
+ DISPLAY_VER(i915) >= 14 ?
+ 1 << 24 : 1 << 16);
ilk_lut_write(crtc_state, PRE_CSC_GAMC_INDEX(pipe), 0);
}
@@ -3573,17 +3582,10 @@ static struct drm_property_blob *glk_read_degamma_lut(struct intel_crtc *crtc)
for (i = 0; i < lut_size; i++) {
u32 val = intel_de_read_fw(dev_priv, PRE_CSC_GAMC_DATA(pipe));
- /*
- * For MTL and beyond, convert back the 24 bit lut values
- * read from HW to 16 bit values to maintain parity with
- * userspace values
- */
if (DISPLAY_VER(dev_priv) >= 14)
- val = change_lut_val_precision(val, 16, 24);
-
- lut[i].red = val;
- lut[i].green = val;
- lut[i].blue = val;
+ mtl_degamma_lut_pack(&lut[i], val);
+ else
+ glk_degamma_lut_pack(&lut[i], val);
}
intel_de_write_fw(dev_priv, PRE_CSC_GAMC_INDEX(pipe),
--
2.41.0
