Commit 3509a03f4dcf7fedb8880180fed3f7f791ce5598
Committed by
Takashi Iwai
Takashi Iwai
1 parent
599ed4b0ae
Exists in
smarc-l5.0.0_1.0.0-ga
and in
5 other branches
ALSA: core: group read of pointer, tstamp and jiffies
Group read of hw_ptr, tstamp and jiffies in a sequence for better correlation. Previous code took timestamp at the end, which could introduce delays between audio time and system time. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Showing 1 changed file with 18 additions and 5 deletions Side-by-side Diff
sound/core/pcm_lib.c
| ... | ... | @@ -313,9 +313,22 @@ |
| 313 | 313 | snd_pcm_uframes_t old_hw_ptr, new_hw_ptr, hw_base; |
| 314 | 314 | snd_pcm_sframes_t hdelta, delta; |
| 315 | 315 | unsigned long jdelta; |
| 316 | + unsigned long curr_jiffies; | |
| 317 | + struct timespec curr_tstamp; | |
| 316 | 318 | |
| 317 | 319 | old_hw_ptr = runtime->status->hw_ptr; |
| 320 | + | |
| 321 | + /* | |
| 322 | + * group pointer, time and jiffies reads to allow for more | |
| 323 | + * accurate correlations/corrections. | |
| 324 | + * The values are stored at the end of this routine after | |
| 325 | + * corrections for hw_ptr position | |
| 326 | + */ | |
| 318 | 327 | pos = substream->ops->pointer(substream); |
| 328 | + curr_jiffies = jiffies; | |
| 329 | + if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) | |
| 330 | + snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp); | |
| 331 | + | |
| 319 | 332 | if (pos == SNDRV_PCM_POS_XRUN) { |
| 320 | 333 | xrun(substream); |
| 321 | 334 | return -EPIPE; |
| ... | ... | @@ -343,7 +356,7 @@ |
| 343 | 356 | delta = runtime->hw_ptr_interrupt + runtime->period_size; |
| 344 | 357 | if (delta > new_hw_ptr) { |
| 345 | 358 | /* check for double acknowledged interrupts */ |
| 346 | - hdelta = jiffies - runtime->hw_ptr_jiffies; | |
| 359 | + hdelta = curr_jiffies - runtime->hw_ptr_jiffies; | |
| 347 | 360 | if (hdelta > runtime->hw_ptr_buffer_jiffies/2) { |
| 348 | 361 | hw_base += runtime->buffer_size; |
| 349 | 362 | if (hw_base >= runtime->boundary) |
| ... | ... | @@ -388,7 +401,7 @@ |
| 388 | 401 | * Without regular period interrupts, we have to check |
| 389 | 402 | * the elapsed time to detect xruns. |
| 390 | 403 | */ |
| 391 | - jdelta = jiffies - runtime->hw_ptr_jiffies; | |
| 404 | + jdelta = curr_jiffies - runtime->hw_ptr_jiffies; | |
| 392 | 405 | if (jdelta < runtime->hw_ptr_buffer_jiffies / 2) |
| 393 | 406 | goto no_delta_check; |
| 394 | 407 | hdelta = jdelta - delta * HZ / runtime->rate; |
| ... | ... | @@ -430,7 +443,7 @@ |
| 430 | 443 | if (hdelta < runtime->delay) |
| 431 | 444 | goto no_jiffies_check; |
| 432 | 445 | hdelta -= runtime->delay; |
| 433 | - jdelta = jiffies - runtime->hw_ptr_jiffies; | |
| 446 | + jdelta = curr_jiffies - runtime->hw_ptr_jiffies; | |
| 434 | 447 | if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) { |
| 435 | 448 | delta = jdelta / |
| 436 | 449 | (((runtime->period_size * HZ) / runtime->rate) |
| 437 | 450 | |
| ... | ... | @@ -492,9 +505,9 @@ |
| 492 | 505 | } |
| 493 | 506 | runtime->hw_ptr_base = hw_base; |
| 494 | 507 | runtime->status->hw_ptr = new_hw_ptr; |
| 495 | - runtime->hw_ptr_jiffies = jiffies; | |
| 508 | + runtime->hw_ptr_jiffies = curr_jiffies; | |
| 496 | 509 | if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) |
| 497 | - snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp); | |
| 510 | + runtime->status->tstamp = curr_tstamp; | |
| 498 | 511 | |
| 499 | 512 | return snd_pcm_update_state(substream, runtime); |
| 500 | 513 | } |