On Fri, Dec 29, 2017 at 08:29:11PM +0530, Uma Shankar wrote:
> From: Johnson Lin <johnson.lin@xxxxxxxxx>
>
> 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.
>
> Signed-off-by: Johnson Lin <johnson.lin@xxxxxxxxx>
> Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_color.c | 29 +++++++++++++++--------------
> 1 file changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
> index aa66e95..55408e2 100644
> --- a/drivers/gpu/drm/i915/intel_color.c
> +++ b/drivers/gpu/drm/i915/intel_color.c
> @@ -84,26 +84,27 @@ 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)
Since your touching pretty much every line anyway, maybe
s/uint64/u64/ etc. all over.
'input' should really be const u64 *.
> {
> int i;
>
> - for (i = 0; i < 9; i++)
> - result[i] = 0;
> + for (i = 0; i < 9; i++) {
> + uint64_t user_coeff = input[i];
> + uint32_t limited_coeff = CTM_COEFF_LIMITED_RANGE;
> + uint32_t abs_coeff = (uint32_t)(clamp_val(
The cast is not needed.
Apart from those nits this lgtm.
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> + 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;
> }
> }
>
> --
> 1.7.9.5
>
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--
Ville Syrjälä
Intel OTC
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