Re: [Intel-gfx] [PATCH 11/11] drm/i915: Create resized LUTs for ivb+ split gamma mode

Nautiyal, Ankit K
2022-11-04T05:20:00Z

Patch looks good to me.

Minor suggestions inline:

On 10/26/2022 5:09 PM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Currently when opeating in split gamma mode we do the
nitpick: 'operating' typo.
> "skip ever other sw LUT entry" trick in the low level
> LUT programming/readout functions. That is very annoying
> and a big hinderance to revamping the color management
> uapi.
>
> Let's get rid of that problem by making half sized copies
> of the software LUTs and plugging those into the internal
> {pre,post}_csc_lut attachment points (instead of the sticking
> the uapi provide sw LUTs there directly).
>
> With this the low level stuff will operate purely in terms
> the hardware LUT sizes, and all uapi nonsense is contained
> to the atomic check phase. The one thing we do lose is
> intel_color_assert_luts() since we no longer have a way to
> check that the uapi LUTs were correctly used when generating
> the internal copies. But that seems like a price worth paying.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_color.c | 81 +++++++++++++++++-----
> 1 file changed, 64 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
> index 33871bfacee7..d48904f90e3a 100644
> --- a/drivers/gpu/drm/i915/display/intel_color.c
> +++ b/drivers/gpu/drm/i915/display/intel_color.c
> @@ -597,6 +597,30 @@ create_linear_lut(struct drm_i915_private *i915, int lut_size)
> return blob;
> }
>
> +static struct drm_property_blob *
> +create_resized_lut(struct drm_i915_private *i915,
> + const struct drm_property_blob *blob_in, int lut_out_size)
> +{
> + int i, lut_in_size = drm_color_lut_size(blob_in);
> + struct drm_property_blob *blob_out;
> + const struct drm_color_lut *lut_in;
> + struct drm_color_lut *lut_out;
> +
> + blob_out = drm_property_create_blob(&i915->drm,
> + sizeof(lut_out[0]) * lut_out_size,
> + NULL);
> + if (IS_ERR(blob_out))
> + return blob_out;
> +
> + lut_in = blob_in->data;
> + lut_out = blob_out->data;
> +
> + for (i = 0; i < lut_out_size; i++)
> + lut_out[i] = lut_in[i * (lut_in_size - 1) / (lut_out_size - 1)];
> +
> + return blob_out;
> +}
> +
> static void i9xx_load_lut_8(struct intel_crtc *crtc,
> const struct drm_property_blob *blob)
> {
> @@ -723,19 +747,14 @@ static void ivb_load_lut_10(struct intel_crtc *crtc,
> u32 prec_index)
> {
> struct drm_i915_private *i915 = to_i915(crtc->base.dev);
> - int hw_lut_size = ivb_lut_10_size(prec_index);
> const struct drm_color_lut *lut = blob->data;
> int i, lut_size = drm_color_lut_size(blob);
> enum pipe pipe = crtc->pipe;
>
> - for (i = 0; i < hw_lut_size; i++) {
> - /* We discard half the user entries in split gamma mode */
> - const struct drm_color_lut *entry =
> - &lut[i * (lut_size - 1) / (hw_lut_size - 1)];
> -
> + for (i = 0; i < lut_size; i++) {
> intel_de_write_fw(i915, PREC_PAL_INDEX(pipe), prec_index++);
> intel_de_write_fw(i915, PREC_PAL_DATA(pipe),
> - ilk_lut_10(entry));
> + ilk_lut_10(&lut[i]));
> }
>
> /*
> @@ -751,7 +770,6 @@ static void bdw_load_lut_10(struct intel_crtc *crtc,
> u32 prec_index)
> {
> struct drm_i915_private *i915 = to_i915(crtc->base.dev);
> - int hw_lut_size = ivb_lut_10_size(prec_index);
> const struct drm_color_lut *lut = blob->data;
> int i, lut_size = drm_color_lut_size(blob);
> enum pipe pipe = crtc->pipe;
> @@ -759,14 +777,9 @@ static void bdw_load_lut_10(struct intel_crtc *crtc,
> intel_de_write_fw(i915, PREC_PAL_INDEX(pipe),
> prec_index | PAL_PREC_AUTO_INCREMENT);
>
> - for (i = 0; i < hw_lut_size; i++) {
> - /* We discard half the user entries in split gamma mode */
> - const struct drm_color_lut *entry =
> - &lut[i * (lut_size - 1) / (hw_lut_size - 1)];
> -
> + for (i = 0; i < lut_size; i++)
> intel_de_write_fw(i915, PREC_PAL_DATA(pipe),
> - ilk_lut_10(entry));
> - }
> + ilk_lut_10(&lut[i]));
>
> /*
> * Reset the index, otherwise it prevents the legacy palette to be
> @@ -1343,7 +1356,7 @@ void intel_color_assert_luts(const struct intel_crtc_state *crtc_state)
> crtc_state->pre_csc_lut != i915->display.color.glk_linear_degamma_lut);
> drm_WARN_ON(&i915->drm,
> crtc_state->post_csc_lut != crtc_state->hw.gamma_lut);
> - } else {
> + } else if (crtc_state->gamma_mode != GAMMA_MODE_MODE_SPLIT) {
> drm_WARN_ON(&i915->drm,
> crtc_state->pre_csc_lut != crtc_state->hw.degamma_lut &&
> crtc_state->pre_csc_lut != crtc_state->hw.gamma_lut);
> @@ -1564,6 +1577,38 @@ static u32 ivb_csc_mode(const struct intel_crtc_state *crtc_state)
> return CSC_POSITION_BEFORE_GAMMA;
> }
>
> +static int ivb_assign_luts(struct intel_crtc_state *crtc_state)
> +{
> + struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
> + struct drm_property_blob *degamma_lut, *gamma_lut;
> +
> + if (crtc_state->gamma_mode != GAMMA_MODE_MODE_SPLIT) {
> + ilk_assign_luts(crtc_state);
> + return 0;
> + }
> +
> + drm_WARN_ON(&i915->drm, drm_color_lut_size(crtc_state->hw.degamma_lut) != 1024);
> + drm_WARN_ON(&i915->drm, drm_color_lut_size(crtc_state->hw.gamma_lut) != 1024);

Does it make sense to use some macro for LUT size for split gamma case
and regular case?

Same thing perhaps can be used in ivb_lut_10_size?

Regards,

Ankit

> +
> + degamma_lut = create_resized_lut(i915, crtc_state->hw.degamma_lut, 512);
> + if (IS_ERR(degamma_lut))
> + return PTR_ERR(degamma_lut);
> +
> + gamma_lut = create_resized_lut(i915, crtc_state->hw.gamma_lut, 512);
> + if (IS_ERR(gamma_lut)) {
> + drm_property_blob_put(degamma_lut);
> + return PTR_ERR(gamma_lut);
> + }
> +
> + drm_property_replace_blob(&crtc_state->pre_csc_lut, degamma_lut);
> + drm_property_replace_blob(&crtc_state->post_csc_lut, gamma_lut);
> +
> + drm_property_blob_put(degamma_lut);
> + drm_property_blob_put(gamma_lut);
> +
> + return 0;
> +}
> +
> static int ivb_color_check(struct intel_crtc_state *crtc_state)
> {
> struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
> @@ -1599,7 +1644,9 @@ static int ivb_color_check(struct intel_crtc_state *crtc_state)
> if (ret)
> return ret;
>
> - ilk_assign_luts(crtc_state);
> + ret = ivb_assign_luts(crtc_state);
> + if (ret)
> + return ret;
>
> crtc_state->preload_luts = intel_can_preload_luts(crtc_state);
>