drm/msm/dsi: Migrate to drm_dsc_compute_rc_parameters()

As per the FIXME this code is entirely duplicate with what is already
provided inside drm_dsc_compute_rc_parameters(), supposedly because that
function was yielding "incorrect" results while in reality the panel
driver(s?) used for testing were providing incorrect parameters.

For example, this code from downstream assumed dsc->bits_per_pixel to
contain an integer value, whereas the upstream drm_dsc_config struct
stores it with 4 fractional bits.  drm_dsc_compute_rc_parameters()
already accounts for this feat while the panel driver used for testing
[1] wasn't, hence making drm_dsc_compute_rc_parameters() seem like it
was returning an incorrect result.
Other users of dsc->bits_per_pixel inside dsi_populate_dsc_params() also
treat it in the same erroneous way, and will be addressed in a separate
patch.
In the end, using drm_dsc_compute_rc_parameters() spares both a lot of
duplicate code and erratic behaviour.

[1]: https://git.linaro.org/people/vinod.koul/kernel.git/commit/?h=topic/pixel3_5.18-rc1&id=1d7d98ad564f1ec69e7525e07418918d90f247a1

Fixes: b9080324d6ca ("drm/msm/dsi: add support for dsc data")
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/508939/
Link: https://lore.kernel.org/r/20221026182824.876933-7-marijn.suijten@somainline.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 906ee38..36d42f1 100644 (file)
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -21,6 +21,7 @@
 
 #include <video/mipi_display.h>
 
+#include <drm/display/drm_dsc_helper.h>
 #include <drm/drm_of.h>
 
 #include "dsi.h"
@@ -1749,14 +1750,6 @@ static char bpg_offset[DSC_NUM_BUF_RANGES] = {
 
 static int dsi_populate_dsc_params(struct drm_dsc_config *dsc)
 {
-       int mux_words_size;
-       int groups_per_line, groups_total;
-       int min_rate_buffer_size;
-       int hrd_delay;
-       int pre_num_extra_mux_bits, num_extra_mux_bits;
-       int slice_bits;
-       int data;
-       int final_value, final_scale;
        int i;
 
        dsc->rc_model_size = 8192;
@@ -1782,11 +1775,11 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc)
        if (dsc->bits_per_pixel != 8)
                dsc->initial_offset = 2048;     /* bpp = 12 */
 
-       mux_words_size = 48;            /* bpc == 8/10 */
-       if (dsc->bits_per_component == 12)
-               mux_words_size = 64;
+       if (dsc->bits_per_component <= 10)
+               dsc->mux_word_size = DSC_MUX_WORD_SIZE_8_10_BPC;
+       else
+               dsc->mux_word_size = DSC_MUX_WORD_SIZE_12_BPC;
 
-       dsc->mux_word_size = mux_words_size;
        dsc->initial_xmit_delay = 512;
        dsc->initial_scale_value = 32;
        dsc->first_line_bpg_offset = 12;
@@ -1798,52 +1791,7 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc)
        dsc->rc_quant_incr_limit0 = 11;
        dsc->rc_quant_incr_limit1 = 11;
 
-       /* FIXME: need to call drm_dsc_compute_rc_parameters() so that rest of
-        * params are calculated
-        */
-       groups_per_line = DIV_ROUND_UP(dsc->slice_width, 3);
-       dsc->slice_chunk_size = DIV_ROUND_UP(dsc->slice_width * dsc->bits_per_pixel, 8);
-
-       /* rbs-min */
-       min_rate_buffer_size =  dsc->rc_model_size - dsc->initial_offset +
-                               dsc->initial_xmit_delay * dsc->bits_per_pixel +
-                               groups_per_line * dsc->first_line_bpg_offset;
-
-       hrd_delay = DIV_ROUND_UP(min_rate_buffer_size, dsc->bits_per_pixel);
-
-       dsc->initial_dec_delay = hrd_delay - dsc->initial_xmit_delay;
-
-       dsc->initial_scale_value = 8 * dsc->rc_model_size /
-                                      (dsc->rc_model_size - dsc->initial_offset);
-
-       slice_bits = 8 * dsc->slice_chunk_size * dsc->slice_height;
-
-       groups_total = groups_per_line * dsc->slice_height;
-
-       data = dsc->first_line_bpg_offset * 2048;
-
-       dsc->nfl_bpg_offset = DIV_ROUND_UP(data, (dsc->slice_height - 1));
-
-       pre_num_extra_mux_bits = 3 * (mux_words_size + (4 * dsc->bits_per_component + 4) - 2);
-
-       num_extra_mux_bits = pre_num_extra_mux_bits - (mux_words_size -
-                            ((slice_bits - pre_num_extra_mux_bits) % mux_words_size));
-
-       data = 2048 * (dsc->rc_model_size - dsc->initial_offset + num_extra_mux_bits);
-       dsc->slice_bpg_offset = DIV_ROUND_UP(data, groups_total);
-
-       data = dsc->initial_xmit_delay * dsc->bits_per_pixel;
-       final_value =  dsc->rc_model_size - data + num_extra_mux_bits;
-       dsc->final_offset = final_value;
-
-       final_scale = 8 * dsc->rc_model_size / (dsc->rc_model_size - final_value);
-
-       data = (final_scale - 9) * (dsc->nfl_bpg_offset + dsc->slice_bpg_offset);
-       dsc->scale_increment_interval = (2048 * dsc->final_offset) / data;
-
-       dsc->scale_decrement_interval = groups_per_line / (dsc->initial_scale_value - 8);
-
-       return 0;
+       return drm_dsc_compute_rc_parameters(dsc);
 }
 
 static int dsi_host_parse_dt(struct msm_dsi_host *msm_host)