root/drivers/gpu/drm/drm_dsc.c

DEFINITIONS

1. drm_dsc_dp_pps_header_init
2. drm_dsc_pps_payload_pack
3. drm_dsc_compute_rc_parameters

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright © 2018 Intel Corp
   4  *
   5  * Author:
   6  * Manasi Navare <manasi.d.navare@intel.com>
   7  */
   8 
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/errno.h>
  13 #include <linux/byteorder/generic.h>
  14 #include <drm/drm_print.h>
  15 #include <drm/drm_dp_helper.h>
  16 #include <drm/drm_dsc.h>
  17 
  18 /**
  19  * DOC: dsc helpers
  20  *
  21  * VESA specification for DP 1.4 adds a new feature called Display Stream
  22  * Compression (DSC) used to compress the pixel bits before sending it on
  23  * DP/eDP/MIPI DSI interface. DSC is required to be enabled so that the existing
  24  * display interfaces can support high resolutions at higher frames rates uisng
  25  * the maximum available link capacity of these interfaces.
  26  *
  27  * These functions contain some common logic and helpers to deal with VESA
  28  * Display Stream Compression standard required for DSC on Display Port/eDP or
  29  * MIPI display interfaces.
  30  */
  31 
  32 /**
  33  * drm_dsc_dp_pps_header_init() - Initializes the PPS Header
  34  * for DisplayPort as per the DP 1.4 spec.
  35  * @pps_header: Secondary data packet header for DSC Picture
  36  *              Parameter Set as defined in &struct dp_sdp_header
  37  *
  38  * DP 1.4 spec defines the secondary data packet for sending the
  39  * picture parameter infoframes from the source to the sink.
  40  * This function populates the SDP header defined in
  41  * &struct dp_sdp_header.
  42  */
  43 void drm_dsc_dp_pps_header_init(struct dp_sdp_header *pps_header)
  44 {
  45         memset(pps_header, 0, sizeof(*pps_header));
  46 
  47         pps_header->HB1 = DP_SDP_PPS;
  48         pps_header->HB2 = DP_SDP_PPS_HEADER_PAYLOAD_BYTES_MINUS_1;
  49 }
  50 EXPORT_SYMBOL(drm_dsc_dp_pps_header_init);
  51 
  52 /**
  53  * drm_dsc_pps_payload_pack() - Populates the DSC PPS
  54  *
  55  * @pps_payload:
  56  * Bitwise struct for DSC Picture Parameter Set. This is defined
  57  * by &struct drm_dsc_picture_parameter_set
  58  * @dsc_cfg:
  59  * DSC Configuration data filled by driver as defined by
  60  * &struct drm_dsc_config
  61  *
  62  * DSC source device sends a picture parameter set (PPS) containing the
  63  * information required by the sink to decode the compressed frame. Driver
  64  * populates the DSC PPS struct using the DSC configuration parameters in
  65  * the order expected by the DSC Display Sink device. For the DSC, the sink
  66  * device expects the PPS payload in big endian format for fields
  67  * that span more than 1 byte.
  68  */
  69 void drm_dsc_pps_payload_pack(struct drm_dsc_picture_parameter_set *pps_payload,
  70                                 const struct drm_dsc_config *dsc_cfg)
  71 {
  72         int i;
  73 
  74         /* Protect against someone accidently changing struct size */
  75         BUILD_BUG_ON(sizeof(*pps_payload) !=
  76                      DP_SDP_PPS_HEADER_PAYLOAD_BYTES_MINUS_1 + 1);
  77 
  78         memset(pps_payload, 0, sizeof(*pps_payload));
  79 
  80         /* PPS 0 */
  81         pps_payload->dsc_version =
  82                 dsc_cfg->dsc_version_minor |
  83                 dsc_cfg->dsc_version_major << DSC_PPS_VERSION_MAJOR_SHIFT;
  84 
  85         /* PPS 1, 2 is 0 */
  86 
  87         /* PPS 3 */
  88         pps_payload->pps_3 =
  89                 dsc_cfg->line_buf_depth |
  90                 dsc_cfg->bits_per_component << DSC_PPS_BPC_SHIFT;
  91 
  92         /* PPS 4 */
  93         pps_payload->pps_4 =
  94                 ((dsc_cfg->bits_per_pixel & DSC_PPS_BPP_HIGH_MASK) >>
  95                  DSC_PPS_MSB_SHIFT) |
  96                 dsc_cfg->vbr_enable << DSC_PPS_VBR_EN_SHIFT |
  97                 dsc_cfg->simple_422 << DSC_PPS_SIMPLE422_SHIFT |
  98                 dsc_cfg->convert_rgb << DSC_PPS_CONVERT_RGB_SHIFT |
  99                 dsc_cfg->block_pred_enable << DSC_PPS_BLOCK_PRED_EN_SHIFT;
 100 
 101         /* PPS 5 */
 102         pps_payload->bits_per_pixel_low =
 103                 (dsc_cfg->bits_per_pixel & DSC_PPS_LSB_MASK);
 104 
 105         /*
 106          * The DSC panel expects the PPS packet to have big endian format
 107          * for data spanning 2 bytes. Use a macro cpu_to_be16() to convert
 108          * to big endian format. If format is little endian, it will swap
 109          * bytes to convert to Big endian else keep it unchanged.
 110          */
 111 
 112         /* PPS 6, 7 */
 113         pps_payload->pic_height = cpu_to_be16(dsc_cfg->pic_height);
 114 
 115         /* PPS 8, 9 */
 116         pps_payload->pic_width = cpu_to_be16(dsc_cfg->pic_width);
 117 
 118         /* PPS 10, 11 */
 119         pps_payload->slice_height = cpu_to_be16(dsc_cfg->slice_height);
 120 
 121         /* PPS 12, 13 */
 122         pps_payload->slice_width = cpu_to_be16(dsc_cfg->slice_width);
 123 
 124         /* PPS 14, 15 */
 125         pps_payload->chunk_size = cpu_to_be16(dsc_cfg->slice_chunk_size);
 126 
 127         /* PPS 16 */
 128         pps_payload->initial_xmit_delay_high =
 129                 ((dsc_cfg->initial_xmit_delay &
 130                   DSC_PPS_INIT_XMIT_DELAY_HIGH_MASK) >>
 131                  DSC_PPS_MSB_SHIFT);
 132 
 133         /* PPS 17 */
 134         pps_payload->initial_xmit_delay_low =
 135                 (dsc_cfg->initial_xmit_delay & DSC_PPS_LSB_MASK);
 136 
 137         /* PPS 18, 19 */
 138         pps_payload->initial_dec_delay =
 139                 cpu_to_be16(dsc_cfg->initial_dec_delay);
 140 
 141         /* PPS 20 is 0 */
 142 
 143         /* PPS 21 */
 144         pps_payload->initial_scale_value =
 145                 dsc_cfg->initial_scale_value;
 146 
 147         /* PPS 22, 23 */
 148         pps_payload->scale_increment_interval =
 149                 cpu_to_be16(dsc_cfg->scale_increment_interval);
 150 
 151         /* PPS 24 */
 152         pps_payload->scale_decrement_interval_high =
 153                 ((dsc_cfg->scale_decrement_interval &
 154                   DSC_PPS_SCALE_DEC_INT_HIGH_MASK) >>
 155                  DSC_PPS_MSB_SHIFT);
 156 
 157         /* PPS 25 */
 158         pps_payload->scale_decrement_interval_low =
 159                 (dsc_cfg->scale_decrement_interval & DSC_PPS_LSB_MASK);
 160 
 161         /* PPS 26[7:0], PPS 27[7:5] RESERVED */
 162 
 163         /* PPS 27 */
 164         pps_payload->first_line_bpg_offset =
 165                 dsc_cfg->first_line_bpg_offset;
 166 
 167         /* PPS 28, 29 */
 168         pps_payload->nfl_bpg_offset =
 169                 cpu_to_be16(dsc_cfg->nfl_bpg_offset);
 170 
 171         /* PPS 30, 31 */
 172         pps_payload->slice_bpg_offset =
 173                 cpu_to_be16(dsc_cfg->slice_bpg_offset);
 174 
 175         /* PPS 32, 33 */
 176         pps_payload->initial_offset =
 177                 cpu_to_be16(dsc_cfg->initial_offset);
 178 
 179         /* PPS 34, 35 */
 180         pps_payload->final_offset = cpu_to_be16(dsc_cfg->final_offset);
 181 
 182         /* PPS 36 */
 183         pps_payload->flatness_min_qp = dsc_cfg->flatness_min_qp;
 184 
 185         /* PPS 37 */
 186         pps_payload->flatness_max_qp = dsc_cfg->flatness_max_qp;
 187 
 188         /* PPS 38, 39 */
 189         pps_payload->rc_model_size =
 190                 cpu_to_be16(DSC_RC_MODEL_SIZE_CONST);
 191 
 192         /* PPS 40 */
 193         pps_payload->rc_edge_factor = DSC_RC_EDGE_FACTOR_CONST;
 194 
 195         /* PPS 41 */
 196         pps_payload->rc_quant_incr_limit0 =
 197                 dsc_cfg->rc_quant_incr_limit0;
 198 
 199         /* PPS 42 */
 200         pps_payload->rc_quant_incr_limit1 =
 201                 dsc_cfg->rc_quant_incr_limit1;
 202 
 203         /* PPS 43 */
 204         pps_payload->rc_tgt_offset = DSC_RC_TGT_OFFSET_LO_CONST |
 205                 DSC_RC_TGT_OFFSET_HI_CONST << DSC_PPS_RC_TGT_OFFSET_HI_SHIFT;
 206 
 207         /* PPS 44 - 57 */
 208         for (i = 0; i < DSC_NUM_BUF_RANGES - 1; i++)
 209                 pps_payload->rc_buf_thresh[i] =
 210                         dsc_cfg->rc_buf_thresh[i];
 211 
 212         /* PPS 58 - 87 */
 213         /*
 214          * For DSC sink programming the RC Range parameter fields
 215          * are as follows: Min_qp[15:11], max_qp[10:6], offset[5:0]
 216          */
 217         for (i = 0; i < DSC_NUM_BUF_RANGES; i++) {
 218                 pps_payload->rc_range_parameters[i] =
 219                         ((dsc_cfg->rc_range_params[i].range_min_qp <<
 220                           DSC_PPS_RC_RANGE_MINQP_SHIFT) |
 221                          (dsc_cfg->rc_range_params[i].range_max_qp <<
 222                           DSC_PPS_RC_RANGE_MAXQP_SHIFT) |
 223                          (dsc_cfg->rc_range_params[i].range_bpg_offset));
 224                 pps_payload->rc_range_parameters[i] =
 225                         cpu_to_be16(pps_payload->rc_range_parameters[i]);
 226         }
 227 
 228         /* PPS 88 */
 229         pps_payload->native_422_420 = dsc_cfg->native_422 |
 230                 dsc_cfg->native_420 << DSC_PPS_NATIVE_420_SHIFT;
 231 
 232         /* PPS 89 */
 233         pps_payload->second_line_bpg_offset =
 234                 dsc_cfg->second_line_bpg_offset;
 235 
 236         /* PPS 90, 91 */
 237         pps_payload->nsl_bpg_offset =
 238                 cpu_to_be16(dsc_cfg->nsl_bpg_offset);
 239 
 240         /* PPS 92, 93 */
 241         pps_payload->second_line_offset_adj =
 242                 cpu_to_be16(dsc_cfg->second_line_offset_adj);
 243 
 244         /* PPS 94 - 127 are O */
 245 }
 246 EXPORT_SYMBOL(drm_dsc_pps_payload_pack);
 247 
 248 /**
 249  * drm_dsc_compute_rc_parameters() - Write rate control
 250  * parameters to the dsc configuration defined in
 251  * &struct drm_dsc_config in accordance with the DSC 1.2
 252  * specification. Some configuration fields must be present
 253  * beforehand.
 254  *
 255  * @vdsc_cfg:
 256  * DSC Configuration data partially filled by driver
 257  */
 258 int drm_dsc_compute_rc_parameters(struct drm_dsc_config *vdsc_cfg)
 259 {
 260         unsigned long groups_per_line = 0;
 261         unsigned long groups_total = 0;
 262         unsigned long num_extra_mux_bits = 0;
 263         unsigned long slice_bits = 0;
 264         unsigned long hrd_delay = 0;
 265         unsigned long final_scale = 0;
 266         unsigned long rbs_min = 0;
 267 
 268         if (vdsc_cfg->native_420 || vdsc_cfg->native_422) {
 269                 /* Number of groups used to code each line of a slice */
 270                 groups_per_line = DIV_ROUND_UP(vdsc_cfg->slice_width / 2,
 271                                                DSC_RC_PIXELS_PER_GROUP);
 272 
 273                 /* chunksize in Bytes */
 274                 vdsc_cfg->slice_chunk_size = DIV_ROUND_UP(vdsc_cfg->slice_width / 2 *
 275                                                           vdsc_cfg->bits_per_pixel,
 276                                                           (8 * 16));
 277         } else {
 278                 /* Number of groups used to code each line of a slice */
 279                 groups_per_line = DIV_ROUND_UP(vdsc_cfg->slice_width,
 280                                                DSC_RC_PIXELS_PER_GROUP);
 281 
 282                 /* chunksize in Bytes */
 283                 vdsc_cfg->slice_chunk_size = DIV_ROUND_UP(vdsc_cfg->slice_width *
 284                                                           vdsc_cfg->bits_per_pixel,
 285                                                           (8 * 16));
 286         }
 287 
 288         if (vdsc_cfg->convert_rgb)
 289                 num_extra_mux_bits = 3 * (vdsc_cfg->mux_word_size +
 290                                           (4 * vdsc_cfg->bits_per_component + 4)
 291                                           - 2);
 292         else if (vdsc_cfg->native_422)
 293                 num_extra_mux_bits = 4 * vdsc_cfg->mux_word_size +
 294                         (4 * vdsc_cfg->bits_per_component + 4) +
 295                         3 * (4 * vdsc_cfg->bits_per_component) - 2;
 296         else
 297                 num_extra_mux_bits = 3 * vdsc_cfg->mux_word_size +
 298                         (4 * vdsc_cfg->bits_per_component + 4) +
 299                         2 * (4 * vdsc_cfg->bits_per_component) - 2;
 300         /* Number of bits in one Slice */
 301         slice_bits = 8 * vdsc_cfg->slice_chunk_size * vdsc_cfg->slice_height;
 302 
 303         while ((num_extra_mux_bits > 0) &&
 304                ((slice_bits - num_extra_mux_bits) % vdsc_cfg->mux_word_size))
 305                 num_extra_mux_bits--;
 306 
 307         if (groups_per_line < vdsc_cfg->initial_scale_value - 8)
 308                 vdsc_cfg->initial_scale_value = groups_per_line + 8;
 309 
 310         /* scale_decrement_interval calculation according to DSC spec 1.11 */
 311         if (vdsc_cfg->initial_scale_value > 8)
 312                 vdsc_cfg->scale_decrement_interval = groups_per_line /
 313                         (vdsc_cfg->initial_scale_value - 8);
 314         else
 315                 vdsc_cfg->scale_decrement_interval = DSC_SCALE_DECREMENT_INTERVAL_MAX;
 316 
 317         vdsc_cfg->final_offset = vdsc_cfg->rc_model_size -
 318                 (vdsc_cfg->initial_xmit_delay *
 319                  vdsc_cfg->bits_per_pixel + 8) / 16 + num_extra_mux_bits;
 320 
 321         if (vdsc_cfg->final_offset >= vdsc_cfg->rc_model_size) {
 322                 DRM_DEBUG_KMS("FinalOfs < RcModelSze for this InitialXmitDelay\n");
 323                 return -ERANGE;
 324         }
 325 
 326         final_scale = (vdsc_cfg->rc_model_size * 8) /
 327                 (vdsc_cfg->rc_model_size - vdsc_cfg->final_offset);
 328         if (vdsc_cfg->slice_height > 1)
 329                 /*
 330                  * NflBpgOffset is 16 bit value with 11 fractional bits
 331                  * hence we multiply by 2^11 for preserving the
 332                  * fractional part
 333                  */
 334                 vdsc_cfg->nfl_bpg_offset = DIV_ROUND_UP((vdsc_cfg->first_line_bpg_offset << 11),
 335                                                         (vdsc_cfg->slice_height - 1));
 336         else
 337                 vdsc_cfg->nfl_bpg_offset = 0;
 338 
 339         /* 2^16 - 1 */
 340         if (vdsc_cfg->nfl_bpg_offset > 65535) {
 341                 DRM_DEBUG_KMS("NflBpgOffset is too large for this slice height\n");
 342                 return -ERANGE;
 343         }
 344 
 345         /* Number of groups used to code the entire slice */
 346         groups_total = groups_per_line * vdsc_cfg->slice_height;
 347 
 348         /* slice_bpg_offset is 16 bit value with 11 fractional bits */
 349         vdsc_cfg->slice_bpg_offset = DIV_ROUND_UP(((vdsc_cfg->rc_model_size -
 350                                                     vdsc_cfg->initial_offset +
 351                                                     num_extra_mux_bits) << 11),
 352                                                   groups_total);
 353 
 354         if (final_scale > 9) {
 355                 /*
 356                  * ScaleIncrementInterval =
 357                  * finaloffset/((NflBpgOffset + SliceBpgOffset)*8(finalscale - 1.125))
 358                  * as (NflBpgOffset + SliceBpgOffset) has 11 bit fractional value,
 359                  * we need divide by 2^11 from pstDscCfg values
 360                  */
 361                 vdsc_cfg->scale_increment_interval =
 362                                 (vdsc_cfg->final_offset * (1 << 11)) /
 363                                 ((vdsc_cfg->nfl_bpg_offset +
 364                                 vdsc_cfg->slice_bpg_offset) *
 365                                 (final_scale - 9));
 366         } else {
 367                 /*
 368                  * If finalScaleValue is less than or equal to 9, a value of 0 should
 369                  * be used to disable the scale increment at the end of the slice
 370                  */
 371                 vdsc_cfg->scale_increment_interval = 0;
 372         }
 373 
 374         if (vdsc_cfg->scale_increment_interval > 65535) {
 375                 DRM_DEBUG_KMS("ScaleIncrementInterval is large for slice height\n");
 376                 return -ERANGE;
 377         }
 378 
 379         /*
 380          * DSC spec mentions that bits_per_pixel specifies the target
 381          * bits/pixel (bpp) rate that is used by the encoder,
 382          * in steps of 1/16 of a bit per pixel
 383          */
 384         rbs_min = vdsc_cfg->rc_model_size - vdsc_cfg->initial_offset +
 385                 DIV_ROUND_UP(vdsc_cfg->initial_xmit_delay *
 386                              vdsc_cfg->bits_per_pixel, 16) +
 387                 groups_per_line * vdsc_cfg->first_line_bpg_offset;
 388 
 389         hrd_delay = DIV_ROUND_UP((rbs_min * 16), vdsc_cfg->bits_per_pixel);
 390         vdsc_cfg->rc_bits = (hrd_delay * vdsc_cfg->bits_per_pixel) / 16;
 391         vdsc_cfg->initial_dec_delay = hrd_delay - vdsc_cfg->initial_xmit_delay;
 392 
 393         return 0;
 394 }
 395 EXPORT_SYMBOL(drm_dsc_compute_rc_parameters);