drivers/media/platform/vivid/vivid-sdr-cap.c

   1 /*
   2  * vivid-sdr-cap.c - software defined radio support functions.
   3  *
   4  * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * This program is free software; you may redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  17  * SOFTWARE.
  18  */
  19
  20 #include <linux/errno.h>
  21 #include <linux/kernel.h>
  22 #include <linux/delay.h>
  23 #include <linux/kthread.h>
  24 #include <linux/freezer.h>
  25 #include <linux/math64.h>
  26 #include <linux/videodev2.h>
  27 #include <linux/v4l2-dv-timings.h>
  28 #include <media/v4l2-common.h>
  29 #include <media/v4l2-event.h>
  30 #include <media/v4l2-dv-timings.h>
  31 #include <linux/fixp-arith.h>
  32
  33 #include "vivid-core.h"
  34 #include "vivid-ctrls.h"
  35 #include "vivid-sdr-cap.h"
  36
  37 /* stream formats */
  38 struct vivid_format {
  39         u32     pixelformat;
  40         u32     buffersize;
  41 };
  42
  43 /* format descriptions for capture and preview */
  44 static const struct vivid_format formats[] = {
  45         {
  46                 .pixelformat    = V4L2_SDR_FMT_CU8,
  47                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  48         }, {
  49                 .pixelformat    = V4L2_SDR_FMT_CS8,
  50                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  51         },
  52 };
  53
  54 static const unsigned int NUM_FORMATS = ARRAY_SIZE(formats);
  55
  56 static const struct v4l2_frequency_band bands_adc[] = {
  57         {
  58                 .tuner = 0,
  59                 .type = V4L2_TUNER_ADC,
  60                 .index = 0,
  61                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  62                 .rangelow   =  300000,
  63                 .rangehigh  =  300000,
  64         },
  65         {
  66                 .tuner = 0,
  67                 .type = V4L2_TUNER_ADC,
  68                 .index = 1,
  69                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  70                 .rangelow   =  900001,
  71                 .rangehigh  = 2800000,
  72         },
  73         {
  74                 .tuner = 0,
  75                 .type = V4L2_TUNER_ADC,
  76                 .index = 2,
  77                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  78                 .rangelow   = 3200000,
  79                 .rangehigh  = 3200000,
  80         },
  81 };
  82
  83 /* ADC band midpoints */
  84 #define BAND_ADC_0 ((bands_adc[0].rangehigh + bands_adc[1].rangelow) / 2)
  85 #define BAND_ADC_1 ((bands_adc[1].rangehigh + bands_adc[2].rangelow) / 2)
  86
  87 static const struct v4l2_frequency_band bands_fm[] = {
  88         {
  89                 .tuner = 1,
  90                 .type = V4L2_TUNER_RF,
  91                 .index = 0,
  92                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  93                 .rangelow   =    50000000,
  94                 .rangehigh  =  2000000000,
  95         },
  96 };
  97
  98 static void vivid_thread_sdr_cap_tick(struct vivid_dev *dev)
  99 {
 100         struct vivid_buffer *sdr_cap_buf = NULL;
 101
 102         dprintk(dev, 1, "SDR Capture Thread Tick\n");
 103
 104         /* Drop a certain percentage of buffers. */
 105         if (dev->perc_dropped_buffers &&
 106             prandom_u32_max(100) < dev->perc_dropped_buffers)
 107                 return;
 108
 109         spin_lock(&dev->slock);
 110         if (!list_empty(&dev->sdr_cap_active)) {
 111                 sdr_cap_buf = list_entry(dev->sdr_cap_active.next,
 112                                          struct vivid_buffer, list);
 113                 list_del(&sdr_cap_buf->list);
 114         }
 115         spin_unlock(&dev->slock);
 116
 117         if (sdr_cap_buf) {
 118                 sdr_cap_buf->vb.sequence = dev->sdr_cap_seq_count;
 119                 vivid_sdr_cap_process(dev, sdr_cap_buf);
 120                 v4l2_get_timestamp(&sdr_cap_buf->vb.timestamp);
 121                 sdr_cap_buf->vb.timestamp.tv_sec += dev->time_wrap_offset;
 122                 vb2_buffer_done(&sdr_cap_buf->vb.vb2_buf, dev->dqbuf_error ?
 123                                 VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
 124                 dev->dqbuf_error = false;
 125         }
 126 }
 127
 128 static int vivid_thread_sdr_cap(void *data)
 129 {
 130         struct vivid_dev *dev = data;
 131         u64 samples_since_start;
 132         u64 buffers_since_start;
 133         u64 next_jiffies_since_start;
 134         unsigned long jiffies_since_start;
 135         unsigned long cur_jiffies;
 136         unsigned wait_jiffies;
 137
 138         dprintk(dev, 1, "SDR Capture Thread Start\n");
 139
 140         set_freezable();
 141
 142         /* Resets frame counters */
 143         dev->sdr_cap_seq_offset = 0;
 144         if (dev->seq_wrap)
 145                 dev->sdr_cap_seq_offset = 0xffffff80U;
 146         dev->jiffies_sdr_cap = jiffies;
 147         dev->sdr_cap_seq_resync = false;
 148
 149         for (;;) {
 150                 try_to_freeze();
 151                 if (kthread_should_stop())
 152                         break;
 153
 154                 if (!mutex_trylock(&dev->mutex)) {
 155                         schedule_timeout_uninterruptible(1);
 156                         continue;
 157                 }
 158
 159                 cur_jiffies = jiffies;
 160                 if (dev->sdr_cap_seq_resync) {
 161                         dev->jiffies_sdr_cap = cur_jiffies;
 162                         dev->sdr_cap_seq_offset = dev->sdr_cap_seq_count + 1;
 163                         dev->sdr_cap_seq_count = 0;
 164                         dev->sdr_cap_seq_resync = false;
 165                 }
 166                 /* Calculate the number of jiffies since we started streaming */
 167                 jiffies_since_start = cur_jiffies - dev->jiffies_sdr_cap;
 168                 /* Get the number of buffers streamed since the start */
 169                 buffers_since_start =
 170                         (u64)jiffies_since_start * dev->sdr_adc_freq +
 171                                       (HZ * SDR_CAP_SAMPLES_PER_BUF) / 2;
 172                 do_div(buffers_since_start, HZ * SDR_CAP_SAMPLES_PER_BUF);
 173
 174                 /*
 175                  * After more than 0xf0000000 (rounded down to a multiple of
 176                  * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
 177                  * jiffies have passed since we started streaming reset the
 178                  * counters and keep track of the sequence offset.
 179                  */
 180                 if (jiffies_since_start > JIFFIES_RESYNC) {
 181                         dev->jiffies_sdr_cap = cur_jiffies;
 182                         dev->sdr_cap_seq_offset = buffers_since_start;
 183                         buffers_since_start = 0;
 184                 }
 185                 dev->sdr_cap_seq_count =
 186                         buffers_since_start + dev->sdr_cap_seq_offset;
 187
 188                 vivid_thread_sdr_cap_tick(dev);
 189                 mutex_unlock(&dev->mutex);
 190
 191                 /*
 192                  * Calculate the number of samples streamed since we started,
 193                  * not including the current buffer.
 194                  */
 195                 samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
 196
 197                 /* And the number of jiffies since we started */
 198                 jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
 199
 200                 /* Increase by the number of samples in one buffer */
 201                 samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
 202                 /*
 203                  * Calculate when that next buffer is supposed to start
 204                  * in jiffies since we started streaming.
 205                  */
 206                 next_jiffies_since_start = samples_since_start * HZ +
 207                                            dev->sdr_adc_freq / 2;
 208                 do_div(next_jiffies_since_start, dev->sdr_adc_freq);
 209                 /* If it is in the past, then just schedule asap */
 210                 if (next_jiffies_since_start < jiffies_since_start)
 211                         next_jiffies_since_start = jiffies_since_start;
 212
 213                 wait_jiffies = next_jiffies_since_start - jiffies_since_start;
 214                 schedule_timeout_interruptible(wait_jiffies ? wait_jiffies : 1);
 215         }
 216         dprintk(dev, 1, "SDR Capture Thread End\n");
 217         return 0;
 218 }
 219
 220 static int sdr_cap_queue_setup(struct vb2_queue *vq, const void *parg,
 221                        unsigned *nbuffers, unsigned *nplanes,
 222                        unsigned sizes[], void *alloc_ctxs[])
 223 {
 224         /* 2 = max 16-bit sample returned */
 225         sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
 226         *nplanes = 1;
 227         return 0;
 228 }
 229
 230 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
 231 {
 232         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 233         unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
 234
 235         dprintk(dev, 1, "%s\n", __func__);
 236
 237         if (dev->buf_prepare_error) {
 238                 /*
 239                  * Error injection: test what happens if buf_prepare() returns
 240                  * an error.
 241                  */
 242                 dev->buf_prepare_error = false;
 243                 return -EINVAL;
 244         }
 245         if (vb2_plane_size(vb, 0) < size) {
 246                 dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
 247                                 __func__, vb2_plane_size(vb, 0), size);
 248                 return -EINVAL;
 249         }
 250         vb2_set_plane_payload(vb, 0, size);
 251
 252         return 0;
 253 }
 254
 255 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
 256 {
 257         struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
 258         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 259         struct vivid_buffer *buf = container_of(vbuf, struct vivid_buffer, vb);
 260
 261         dprintk(dev, 1, "%s\n", __func__);
 262
 263         spin_lock(&dev->slock);
 264         list_add_tail(&buf->list, &dev->sdr_cap_active);
 265         spin_unlock(&dev->slock);
 266 }
 267
 268 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
 269 {
 270         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 271         int err = 0;
 272
 273         dprintk(dev, 1, "%s\n", __func__);
 274         dev->sdr_cap_seq_count = 0;
 275         if (dev->start_streaming_error) {
 276                 dev->start_streaming_error = false;
 277                 err = -EINVAL;
 278         } else if (dev->kthread_sdr_cap == NULL) {
 279                 dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
 280                                 "%s-sdr-cap", dev->v4l2_dev.name);
 281
 282                 if (IS_ERR(dev->kthread_sdr_cap)) {
 283                         v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
 284                         err = PTR_ERR(dev->kthread_sdr_cap);
 285                         dev->kthread_sdr_cap = NULL;
 286                 }
 287         }
 288         if (err) {
 289                 struct vivid_buffer *buf, *tmp;
 290
 291                 list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
 292                         list_del(&buf->list);
 293                         vb2_buffer_done(&buf->vb.vb2_buf,
 294                                         VB2_BUF_STATE_QUEUED);
 295                 }
 296         }
 297         return err;
 298 }
 299
 300 /* abort streaming and wait for last buffer */
 301 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
 302 {
 303         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 304
 305         if (dev->kthread_sdr_cap == NULL)
 306                 return;
 307
 308         while (!list_empty(&dev->sdr_cap_active)) {
 309                 struct vivid_buffer *buf;
 310
 311                 buf = list_entry(dev->sdr_cap_active.next,
 312                                 struct vivid_buffer, list);
 313                 list_del(&buf->list);
 314                 vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
 315         }
 316
 317         /* shutdown control thread */
 318         kthread_stop(dev->kthread_sdr_cap);
 319         dev->kthread_sdr_cap = NULL;
 320 }
 321
 322 const struct vb2_ops vivid_sdr_cap_qops = {
 323         .queue_setup            = sdr_cap_queue_setup,
 324         .buf_prepare            = sdr_cap_buf_prepare,
 325         .buf_queue              = sdr_cap_buf_queue,
 326         .start_streaming        = sdr_cap_start_streaming,
 327         .stop_streaming         = sdr_cap_stop_streaming,
 328         .wait_prepare           = vb2_ops_wait_prepare,
 329         .wait_finish            = vb2_ops_wait_finish,
 330 };
 331
 332 int vivid_sdr_enum_freq_bands(struct file *file, void *fh,
 333                 struct v4l2_frequency_band *band)
 334 {
 335         switch (band->tuner) {
 336         case 0:
 337                 if (band->index >= ARRAY_SIZE(bands_adc))
 338                         return -EINVAL;
 339                 *band = bands_adc[band->index];
 340                 return 0;
 341         case 1:
 342                 if (band->index >= ARRAY_SIZE(bands_fm))
 343                         return -EINVAL;
 344                 *band = bands_fm[band->index];
 345                 return 0;
 346         default:
 347                 return -EINVAL;
 348         }
 349 }
 350
 351 int vivid_sdr_g_frequency(struct file *file, void *fh,
 352                 struct v4l2_frequency *vf)
 353 {
 354         struct vivid_dev *dev = video_drvdata(file);
 355
 356         switch (vf->tuner) {
 357         case 0:
 358                 vf->frequency = dev->sdr_adc_freq;
 359                 vf->type = V4L2_TUNER_ADC;
 360                 return 0;
 361         case 1:
 362                 vf->frequency = dev->sdr_fm_freq;
 363                 vf->type = V4L2_TUNER_RF;
 364                 return 0;
 365         default:
 366                 return -EINVAL;
 367         }
 368 }
 369
 370 int vivid_sdr_s_frequency(struct file *file, void *fh,
 371                 const struct v4l2_frequency *vf)
 372 {
 373         struct vivid_dev *dev = video_drvdata(file);
 374         unsigned freq = vf->frequency;
 375         unsigned band;
 376
 377         switch (vf->tuner) {
 378         case 0:
 379                 if (vf->type != V4L2_TUNER_ADC)
 380                         return -EINVAL;
 381                 if (freq < BAND_ADC_0)
 382                         band = 0;
 383                 else if (freq < BAND_ADC_1)
 384                         band = 1;
 385                 else
 386                         band = 2;
 387
 388                 freq = clamp_t(unsigned, freq,
 389                                 bands_adc[band].rangelow,
 390                                 bands_adc[band].rangehigh);
 391
 392                 if (vb2_is_streaming(&dev->vb_sdr_cap_q) &&
 393                     freq != dev->sdr_adc_freq) {
 394                         /* resync the thread's timings */
 395                         dev->sdr_cap_seq_resync = true;
 396                 }
 397                 dev->sdr_adc_freq = freq;
 398                 return 0;
 399         case 1:
 400                 if (vf->type != V4L2_TUNER_RF)
 401                         return -EINVAL;
 402                 dev->sdr_fm_freq = clamp_t(unsigned, freq,
 403                                 bands_fm[0].rangelow,
 404                                 bands_fm[0].rangehigh);
 405                 return 0;
 406         default:
 407                 return -EINVAL;
 408         }
 409 }
 410
 411 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
 412 {
 413         switch (vt->index) {
 414         case 0:
 415                 strlcpy(vt->name, "ADC", sizeof(vt->name));
 416                 vt->type = V4L2_TUNER_ADC;
 417                 vt->capability =
 418                         V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 419                 vt->rangelow = bands_adc[0].rangelow;
 420                 vt->rangehigh = bands_adc[2].rangehigh;
 421                 return 0;
 422         case 1:
 423                 strlcpy(vt->name, "RF", sizeof(vt->name));
 424                 vt->type = V4L2_TUNER_RF;
 425                 vt->capability =
 426                         V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 427                 vt->rangelow = bands_fm[0].rangelow;
 428                 vt->rangehigh = bands_fm[0].rangehigh;
 429                 return 0;
 430         default:
 431                 return -EINVAL;
 432         }
 433 }
 434
 435 int vivid_sdr_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt)
 436 {
 437         if (vt->index > 1)
 438                 return -EINVAL;
 439         return 0;
 440 }
 441
 442 int vidioc_enum_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_fmtdesc *f)
 443 {
 444         if (f->index >= ARRAY_SIZE(formats))
 445                 return -EINVAL;
 446         f->pixelformat = formats[f->index].pixelformat;
 447         return 0;
 448 }
 449
 450 int vidioc_g_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 451 {
 452         struct vivid_dev *dev = video_drvdata(file);
 453
 454         f->fmt.sdr.pixelformat = dev->sdr_pixelformat;
 455         f->fmt.sdr.buffersize = dev->sdr_buffersize;
 456         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 457         return 0;
 458 }
 459
 460 int vidioc_s_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 461 {
 462         struct vivid_dev *dev = video_drvdata(file);
 463         struct vb2_queue *q = &dev->vb_sdr_cap_q;
 464         int i;
 465
 466         if (vb2_is_busy(q))
 467                 return -EBUSY;
 468
 469         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 470         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 471                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 472                         dev->sdr_pixelformat = formats[i].pixelformat;
 473                         dev->sdr_buffersize = formats[i].buffersize;
 474                         f->fmt.sdr.buffersize = formats[i].buffersize;
 475                         return 0;
 476                 }
 477         }
 478         dev->sdr_pixelformat = formats[0].pixelformat;
 479         dev->sdr_buffersize = formats[0].buffersize;
 480         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 481         f->fmt.sdr.buffersize = formats[0].buffersize;
 482         return 0;
 483 }
 484
 485 int vidioc_try_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 486 {
 487         int i;
 488
 489         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 490         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 491                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 492                         f->fmt.sdr.buffersize = formats[i].buffersize;
 493                         return 0;
 494                 }
 495         }
 496         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 497         f->fmt.sdr.buffersize = formats[0].buffersize;
 498         return 0;
 499 }
 500
 501 #define FIXP_N    (15)
 502 #define FIXP_FRAC (1 << FIXP_N)
 503 #define FIXP_2PI  ((int)(2 * 3.141592653589 * FIXP_FRAC))
 504 #define M_100000PI (3.14159 * 100000)
 505
 506 void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
 507 {
 508         u8 *vbuf = vb2_plane_vaddr(&buf->vb.vb2_buf, 0);
 509         unsigned long i;
 510         unsigned long plane_size = vb2_plane_size(&buf->vb.vb2_buf, 0);
 511         s64 s64tmp;
 512         s32 src_phase_step;
 513         s32 mod_phase_step;
 514         s32 fixp_i;
 515         s32 fixp_q;
 516
 517         /* calculate phase step */
 518         #define BEEP_FREQ 1000 /* 1kHz beep */
 519         src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
 520                                            dev->sdr_adc_freq);
 521
 522         for (i = 0; i < plane_size; i += 2) {
 523                 mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
 524                                                 FIXP_2PI) >> (31 - FIXP_N);
 525
 526                 dev->sdr_fixp_src_phase += src_phase_step;
 527                 s64tmp = (s64) mod_phase_step * dev->sdr_fm_deviation;
 528                 dev->sdr_fixp_mod_phase += div_s64(s64tmp, M_100000PI);
 529
 530                 /*
 531                  * Transfer phase angle to [0, 2xPI] in order to avoid variable
 532                  * overflow and make it suitable for cosine implementation
 533                  * used, which does not support negative angles.
 534                  */
 535                 dev->sdr_fixp_src_phase %= FIXP_2PI;
 536                 dev->sdr_fixp_mod_phase %= FIXP_2PI;
 537
 538                 if (dev->sdr_fixp_mod_phase < 0)
 539                         dev->sdr_fixp_mod_phase += FIXP_2PI;
 540
 541                 fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 542                 fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 543
 544                 /* Normalize fraction values represented with 32 bit precision
 545                  * to fixed point representation with FIXP_N bits */
 546                 fixp_i >>= (31 - FIXP_N);
 547                 fixp_q >>= (31 - FIXP_N);
 548
 549                 switch (dev->sdr_pixelformat) {
 550                 case V4L2_SDR_FMT_CU8:
 551                         /* convert 'fixp float' to u8 [0, +255] */
 552                         /* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
 553                         fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
 554                         fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
 555                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 556                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 557                         break;
 558                 case V4L2_SDR_FMT_CS8:
 559                         /* convert 'fixp float' to s8 [-128, +127] */
 560                         /* s8 = X * 127.5 - 0.5; X is float [-1.0, +1.0] */
 561                         fixp_i = fixp_i * 1275 - FIXP_FRAC * 5;
 562                         fixp_q = fixp_q * 1275 - FIXP_FRAC * 5;
 563                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 564                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 565                         break;
 566                 default:
 567                         break;
 568                 }
 569         }
 570 }