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drm/i915: Fix CHV CGM CSC coefficient sign handling

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The CHV CGM CSC coefficients are in s4.12 two's complement
format. Fix the CTM->CGM conversion to handle that correctly
instead of pretending that the hw coefficients are also
in some sign-magnitude format.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230413164916.4221-4-ville.syrjala@linux.intel.com
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
This commit is contained in:
Ville Syrjälä
2023-04-13 19:49:12 +03:00
parent d9ce4e4307
commit 2587c63aaa
1 changed files with 29 additions and 17 deletions
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46
drivers/gpu/drm/i915/display/intel_color.c
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@@ -568,29 +568,41 @@ static void icl_load_csc_matrix(const struct intel_crtc_state *crtc_state)
icl_update_output_csc(crtc, &crtc_state->output_csc);
}
static u16 ctm_to_twos_complement(u64 coeff, int int_bits, int frac_bits)
{
s64 c = CTM_COEFF_ABS(coeff);
/* leave an extra bit for rounding */
c >>= 32 - frac_bits - 1;
/* round and drop the extra bit */
c = (c + 1) >> 1;
if (CTM_COEFF_NEGATIVE(coeff))
c = -c;
c = clamp(c, -(s64)BIT(int_bits + frac_bits - 1),
(s64)(BIT(int_bits + frac_bits - 1) - 1));
return c & (BIT(int_bits + frac_bits) - 1);
}
/*
* CHV Color Gamut Mapping (CGM) CSC
* |r| | c0 c1 c2 | |r|
* |g| = | c3 c4 c5 | x |g|
* |b| | c6 c7 c8 | |b|
*
* Coefficients are two's complement s4.12.
*/
static void chv_cgm_csc_convert_ctm(const struct intel_crtc_state *crtc_state,
struct intel_csc_matrix *csc)
{
const struct drm_color_ctm *ctm = crtc_state->hw.ctm->data;
int i;
for (i = 0; i < 9; i++) {
u64 abs_coeff = ((1ULL << 63) - 1) & ctm->matrix[i];
/* Round coefficient. */
abs_coeff += 1 << (32 - 13);
/* Clamp to hardware limits. */
abs_coeff = clamp_val(abs_coeff, 0, CTM_COEFF_8_0 - 1);
csc->coeff[i] = 0;
/* Write coefficients in S3.12 format. */
if (ctm->matrix[i] & (1ULL << 63))
csc->coeff[i] |= 1 << 15;
csc->coeff[i] |= ((abs_coeff >> 32) & 7) << 12;
csc->coeff[i] |= (abs_coeff >> 20) & 0xfff;
}
for (i = 0; i < 9; i++)
csc->coeff[i] = ctm_to_twos_complement(ctm->matrix[i], 4, 12);
}
static void chv_load_cgm_csc(struct intel_crtc *crtc,