Commit 2587c63a authored by Ville Syrjälä's avatar Ville Syrjälä
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drm/i915: Fix CHV CGM CSC coefficient sign handling 



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: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230413164916.4221-4-ville.syrjala@linux.intel.com


Reviewed-by: default avatarUma Shankar <uma.shankar@intel.com>
parent d9ce4e43

drivers/gpu/drm/i915/display/intel_color.c

+29 −17
Original line number Diff line number Diff line
@@ -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 void chv_cgm_csc_convert_ctm(const struct intel_crtc_state *crtc_state,

				    struct intel_csc_matrix *csc)

static u16 ctm_to_twos_complement(u64 coeff, int int_bits, int frac_bits)

{

	const struct drm_color_ctm *ctm = crtc_state->hw.ctm->data;

	int i;

	s64 c = CTM_COEFF_ABS(coeff);



	for (i = 0; i < 9; i++) {

		u64 abs_coeff = ((1ULL << 63) - 1) & ctm->matrix[i];

	/* leave an extra bit for rounding */

	c >>= 32 - frac_bits - 1;



		/* Round coefficient. */

		abs_coeff += 1 << (32 - 13);

		/* Clamp to hardware limits. */

		abs_coeff = clamp_val(abs_coeff, 0, CTM_COEFF_8_0 - 1);

	/* round and drop the extra bit */

	c = (c + 1) >> 1;



		csc->coeff[i] = 0;

	if (CTM_COEFF_NEGATIVE(coeff))

		c = -c;



		/* Write coefficients in S3.12 format. */

		if (ctm->matrix[i] & (1ULL << 63))

			csc->coeff[i] |= 1 << 15;

	c = clamp(c, -(s64)BIT(int_bits + frac_bits - 1),

		  (s64)(BIT(int_bits + frac_bits - 1) - 1));



		csc->coeff[i] |= ((abs_coeff >> 32) & 7) << 12;

		csc->coeff[i] |= (abs_coeff >> 20) & 0xfff;

	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++)

		csc->coeff[i] = ctm_to_twos_complement(ctm->matrix[i], 4, 12);

}



static void chv_load_cgm_csc(struct intel_crtc *crtc,