47 	struct snd_pcm_runtime *runtime = substream->runtime;  in snd_pcm_playback_silence()  local
51 	if (runtime->silence_size < runtime->boundary) {  in snd_pcm_playback_silence()
53 		snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);  in snd_pcm_playback_silence()
54 		if (runtime->silence_start != appl_ptr) {  in snd_pcm_playback_silence()
55 			n = appl_ptr - runtime->silence_start;  in snd_pcm_playback_silence()
57 				n += runtime->boundary;  in snd_pcm_playback_silence()
58 			if ((snd_pcm_uframes_t)n < runtime->silence_filled)  in snd_pcm_playback_silence()
59 				runtime->silence_filled -= n;  in snd_pcm_playback_silence()
61 				runtime->silence_filled = 0;  in snd_pcm_playback_silence()
62 			runtime->silence_start = appl_ptr;  in snd_pcm_playback_silence()
64 		if (runtime->silence_filled >= runtime->buffer_size)  in snd_pcm_playback_silence()
66 		noise_dist = snd_pcm_playback_hw_avail(runtime) + runtime->silence_filled;  in snd_pcm_playback_silence()
67 		if (noise_dist >= (snd_pcm_sframes_t) runtime->silence_threshold)  in snd_pcm_playback_silence()
69 		frames = runtime->silence_threshold - noise_dist;  in snd_pcm_playback_silence()
70 		if (frames > runtime->silence_size)  in snd_pcm_playback_silence()
71 			frames = runtime->silence_size;  in snd_pcm_playback_silence()
74 			snd_pcm_sframes_t avail = snd_pcm_playback_hw_avail(runtime);  in snd_pcm_playback_silence()
75 			if (avail > runtime->buffer_size)  in snd_pcm_playback_silence()
76 				avail = runtime->buffer_size;  in snd_pcm_playback_silence()
77 			runtime->silence_filled = avail > 0 ? avail : 0;  in snd_pcm_playback_silence()
78 			runtime->silence_start = (runtime->status->hw_ptr +  in snd_pcm_playback_silence()
79 						  runtime->silence_filled) %  in snd_pcm_playback_silence()
80 						 runtime->boundary;  in snd_pcm_playback_silence()
82 			ofs = runtime->status->hw_ptr;  in snd_pcm_playback_silence()
85 				frames += runtime->boundary;  in snd_pcm_playback_silence()
86 			runtime->silence_filled -= frames;  in snd_pcm_playback_silence()
87 			if ((snd_pcm_sframes_t)runtime->silence_filled < 0) {  in snd_pcm_playback_silence()
88 				runtime->silence_filled = 0;  in snd_pcm_playback_silence()
89 				runtime->silence_start = new_hw_ptr;  in snd_pcm_playback_silence()
91 				runtime->silence_start = ofs;  in snd_pcm_playback_silence()
94 		frames = runtime->buffer_size - runtime->silence_filled;  in snd_pcm_playback_silence()
96 	if (snd_BUG_ON(frames > runtime->buffer_size))  in snd_pcm_playback_silence()
100 	ofs = runtime->silence_start % runtime->buffer_size;  in snd_pcm_playback_silence()
102 		transfer = ofs + frames > runtime->buffer_size ? runtime->buffer_size - ofs : frames;  in snd_pcm_playback_silence()
105 		runtime->silence_filled += transfer;  in snd_pcm_playback_silence()
144 	struct snd_pcm_runtime *runtime = substream->runtime;  in __snd_pcm_xrun()  local
147 	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE)  in __snd_pcm_xrun()
148 		snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);  in __snd_pcm_xrun()
176 			 struct snd_pcm_runtime *runtime)  in snd_pcm_update_state()  argument
181 	if (avail > runtime->avail_max)  in snd_pcm_update_state()
182 		runtime->avail_max = avail;  in snd_pcm_update_state()
183 	if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {  in snd_pcm_update_state()
184 		if (avail >= runtime->buffer_size) {  in snd_pcm_update_state()
189 		if (avail >= runtime->stop_threshold) {  in snd_pcm_update_state()
194 	if (runtime->twake) {  in snd_pcm_update_state()
195 		if (avail >= runtime->twake)  in snd_pcm_update_state()
196 			wake_up(&runtime->tsleep);  in snd_pcm_update_state()
197 	} else if (avail >= runtime->control->avail_min)  in snd_pcm_update_state()
198 		wake_up(&runtime->sleep);  in snd_pcm_update_state()
206 	struct snd_pcm_runtime *runtime = substream->runtime;  in update_audio_tstamp()  local
210 	if (runtime->tstamp_mode != SNDRV_PCM_TSTAMP_ENABLE)  in update_audio_tstamp()
214 		(runtime->audio_tstamp_report.actual_type ==  in update_audio_tstamp()
222 		audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr;  in update_audio_tstamp()
224 		if (runtime->audio_tstamp_config.report_delay) {  in update_audio_tstamp()
226 				audio_frames -=  runtime->delay;  in update_audio_tstamp()
228 				audio_frames +=  runtime->delay;  in update_audio_tstamp()
231 				runtime->rate);  in update_audio_tstamp()
234 	if (!timespec_equal(&runtime->status->audio_tstamp, audio_tstamp)) {  in update_audio_tstamp()
235 		runtime->status->audio_tstamp = *audio_tstamp;  in update_audio_tstamp()
236 		runtime->status->tstamp = *curr_tstamp;  in update_audio_tstamp()
243 	snd_pcm_gettime(substream->runtime, (struct timespec *)&driver_tstamp);  in update_audio_tstamp()
244 	runtime->driver_tstamp = driver_tstamp;  in update_audio_tstamp()
250 	struct snd_pcm_runtime *runtime = substream->runtime;  in snd_pcm_update_hw_ptr0()  local
260 	old_hw_ptr = runtime->status->hw_ptr;  in snd_pcm_update_hw_ptr0()
270 	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {  in snd_pcm_update_hw_ptr0()
272 			(runtime->audio_tstamp_config.type_requested != SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) {  in snd_pcm_update_hw_ptr0()
275 						&runtime->audio_tstamp_config,  in snd_pcm_update_hw_ptr0()
276 						&runtime->audio_tstamp_report);  in snd_pcm_update_hw_ptr0()
279 			if (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)  in snd_pcm_update_hw_ptr0()
280 				snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp);  in snd_pcm_update_hw_ptr0()
282 			snd_pcm_gettime(runtime, (struct timespec *)&curr_tstamp);  in snd_pcm_update_hw_ptr0()
289 	if (pos >= runtime->buffer_size) {  in snd_pcm_update_hw_ptr0()
295 				name, pos, runtime->buffer_size,  in snd_pcm_update_hw_ptr0()
296 				runtime->period_size);  in snd_pcm_update_hw_ptr0()
300 	pos -= pos % runtime->min_align;  in snd_pcm_update_hw_ptr0()
302 	hw_base = runtime->hw_ptr_base;  in snd_pcm_update_hw_ptr0()
307 		delta = runtime->hw_ptr_interrupt + runtime->period_size;  in snd_pcm_update_hw_ptr0()
310 			hdelta = curr_jiffies - runtime->hw_ptr_jiffies;  in snd_pcm_update_hw_ptr0()
311 			if (hdelta > runtime->hw_ptr_buffer_jiffies/2 + 1) {  in snd_pcm_update_hw_ptr0()
312 				hw_base += runtime->buffer_size;  in snd_pcm_update_hw_ptr0()
313 				if (hw_base >= runtime->boundary) {  in snd_pcm_update_hw_ptr0()
325 		hw_base += runtime->buffer_size;  in snd_pcm_update_hw_ptr0()
326 		if (hw_base >= runtime->boundary) {  in snd_pcm_update_hw_ptr0()
335 		delta += runtime->boundary;  in snd_pcm_update_hw_ptr0()
337 	if (runtime->no_period_wakeup) {  in snd_pcm_update_hw_ptr0()
343 		jdelta = curr_jiffies - runtime->hw_ptr_jiffies;  in snd_pcm_update_hw_ptr0()
344 		if (jdelta < runtime->hw_ptr_buffer_jiffies / 2)  in snd_pcm_update_hw_ptr0()
346 		hdelta = jdelta - delta * HZ / runtime->rate;  in snd_pcm_update_hw_ptr0()
347 		xrun_threshold = runtime->hw_ptr_buffer_jiffies / 2 + 1;  in snd_pcm_update_hw_ptr0()
349 			delta += runtime->buffer_size;  in snd_pcm_update_hw_ptr0()
350 			hw_base += runtime->buffer_size;  in snd_pcm_update_hw_ptr0()
351 			if (hw_base >= runtime->boundary) {  in snd_pcm_update_hw_ptr0()
356 			hdelta -= runtime->hw_ptr_buffer_jiffies;  in snd_pcm_update_hw_ptr0()
362 	if (delta >= runtime->buffer_size + runtime->period_size) {  in snd_pcm_update_hw_ptr0()
378 	if (runtime->hw.info & SNDRV_PCM_INFO_BATCH)  in snd_pcm_update_hw_ptr0()
381 	if (hdelta < runtime->delay)  in snd_pcm_update_hw_ptr0()
383 	hdelta -= runtime->delay;  in snd_pcm_update_hw_ptr0()
384 	jdelta = curr_jiffies - runtime->hw_ptr_jiffies;  in snd_pcm_update_hw_ptr0()
385 	if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {  in snd_pcm_update_hw_ptr0()
387 			(((runtime->period_size * HZ) / runtime->rate)  in snd_pcm_update_hw_ptr0()
395 			new_hw_ptr += runtime->period_size;  in snd_pcm_update_hw_ptr0()
396 			if (new_hw_ptr >= runtime->boundary) {  in snd_pcm_update_hw_ptr0()
397 				new_hw_ptr -= runtime->boundary;  in snd_pcm_update_hw_ptr0()
406 			     (long)runtime->period_size, jdelta,  in snd_pcm_update_hw_ptr0()
407 			     ((hdelta * HZ) / runtime->rate), hw_base,  in snd_pcm_update_hw_ptr0()
412 		hw_base = new_hw_ptr - (new_hw_ptr % runtime->buffer_size);  in snd_pcm_update_hw_ptr0()
415 	if (delta > runtime->period_size + runtime->period_size / 2) {  in snd_pcm_update_hw_ptr0()
425 	if (runtime->status->hw_ptr == new_hw_ptr) {  in snd_pcm_update_hw_ptr0()
431 	    runtime->silence_size > 0)  in snd_pcm_update_hw_ptr0()
435 		delta = new_hw_ptr - runtime->hw_ptr_interrupt;  in snd_pcm_update_hw_ptr0()
437 			delta += runtime->boundary;  in snd_pcm_update_hw_ptr0()
438 		delta -= (snd_pcm_uframes_t)delta % runtime->period_size;  in snd_pcm_update_hw_ptr0()
439 		runtime->hw_ptr_interrupt += delta;  in snd_pcm_update_hw_ptr0()
440 		if (runtime->hw_ptr_interrupt >= runtime->boundary)  in snd_pcm_update_hw_ptr0()
441 			runtime->hw_ptr_interrupt -= runtime->boundary;  in snd_pcm_update_hw_ptr0()
443 	runtime->hw_ptr_base = hw_base;  in snd_pcm_update_hw_ptr0()
444 	runtime->status->hw_ptr = new_hw_ptr;  in snd_pcm_update_hw_ptr0()
445 	runtime->hw_ptr_jiffies = curr_jiffies;  in snd_pcm_update_hw_ptr0()
448 		runtime->hw_ptr_wrap += runtime->boundary;  in snd_pcm_update_hw_ptr0()
453 	return snd_pcm_update_state(substream, runtime);  in snd_pcm_update_hw_ptr0()
489 	struct snd_pcm_runtime *runtime = substream->runtime;  in snd_pcm_set_sync()  local
491 	runtime->sync.id32[0] = substream->pcm->card->number;  in snd_pcm_set_sync()
492 	runtime->sync.id32[1] = -1;  in snd_pcm_set_sync()
493 	runtime->sync.id32[2] = -1;  in snd_pcm_set_sync()
494 	runtime->sync.id32[3] = -1;  in snd_pcm_set_sync()
1108 int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond,  in snd_pcm_hw_rule_add()  argument
1113 	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;  in snd_pcm_hw_rule_add()
1162 int snd_pcm_hw_constraint_mask(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,  in snd_pcm_hw_constraint_mask()  argument
1165 	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;  in snd_pcm_hw_constraint_mask()
1184 int snd_pcm_hw_constraint_mask64(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,  in snd_pcm_hw_constraint_mask64()  argument
1187 	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;  in snd_pcm_hw_constraint_mask64()
1208 int snd_pcm_hw_constraint_integer(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var)  in snd_pcm_hw_constraint_integer()  argument
1210 	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;  in snd_pcm_hw_constraint_integer()
1227 int snd_pcm_hw_constraint_minmax(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,  in snd_pcm_hw_constraint_minmax()  argument
1230 	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;  in snd_pcm_hw_constraint_minmax()
1259 int snd_pcm_hw_constraint_list(struct snd_pcm_runtime *runtime,  in snd_pcm_hw_constraint_list()  argument
1264 	return snd_pcm_hw_rule_add(runtime, cond, var,  in snd_pcm_hw_constraint_list()
1290 int snd_pcm_hw_constraint_ranges(struct snd_pcm_runtime *runtime,  in snd_pcm_hw_constraint_ranges()  argument
1295 	return snd_pcm_hw_rule_add(runtime, cond, var,  in snd_pcm_hw_constraint_ranges()
1325 int snd_pcm_hw_constraint_ratnums(struct snd_pcm_runtime *runtime,   in snd_pcm_hw_constraint_ratnums()  argument
1330 	return snd_pcm_hw_rule_add(runtime, cond, var,  in snd_pcm_hw_constraint_ratnums()
1359 int snd_pcm_hw_constraint_ratdens(struct snd_pcm_runtime *runtime,   in snd_pcm_hw_constraint_ratdens()  argument
1364 	return snd_pcm_hw_rule_add(runtime, cond, var,  in snd_pcm_hw_constraint_ratdens()
1403 int snd_pcm_hw_constraint_msbits(struct snd_pcm_runtime *runtime,   in snd_pcm_hw_constraint_msbits()  argument
1409 	return snd_pcm_hw_rule_add(runtime, cond, -1,  in snd_pcm_hw_constraint_msbits()
1432 int snd_pcm_hw_constraint_step(struct snd_pcm_runtime *runtime,  in snd_pcm_hw_constraint_step()  argument
1437 	return snd_pcm_hw_rule_add(runtime, cond, var,   in snd_pcm_hw_constraint_step()
1463 int snd_pcm_hw_constraint_pow2(struct snd_pcm_runtime *runtime,  in snd_pcm_hw_constraint_pow2()  argument
1467 	return snd_pcm_hw_rule_add(runtime, cond, var,   in snd_pcm_hw_constraint_pow2()
1490 int snd_pcm_hw_rule_noresample(struct snd_pcm_runtime *runtime,  in snd_pcm_hw_rule_noresample()  argument
1493 	return snd_pcm_hw_rule_add(runtime, SNDRV_PCM_HW_PARAMS_NORESAMPLE,  in snd_pcm_hw_rule_noresample()
1675 	struct snd_pcm_runtime *runtime = substream->runtime;  in snd_pcm_lib_ioctl_reset()  local
1680 		runtime->status->hw_ptr %= runtime->buffer_size;  in snd_pcm_lib_ioctl_reset()
1682 		runtime->status->hw_ptr = 0;  in snd_pcm_lib_ioctl_reset()
1683 		runtime->hw_ptr_wrap = 0;  in snd_pcm_lib_ioctl_reset()
1693 	struct snd_pcm_runtime *runtime = substream->runtime;  in snd_pcm_lib_ioctl_channel_info()  local
1695 	if (!(runtime->info & SNDRV_PCM_INFO_MMAP)) {  in snd_pcm_lib_ioctl_channel_info()
1699 	width = snd_pcm_format_physical_width(runtime->format);  in snd_pcm_lib_ioctl_channel_info()
1703 	switch (runtime->access) {  in snd_pcm_lib_ioctl_channel_info()
1707 		info->step = runtime->channels * width;  in snd_pcm_lib_ioctl_channel_info()
1712 		size_t size = runtime->dma_bytes / runtime->channels;  in snd_pcm_lib_ioctl_channel_info()
1732 	params->fifo_size = substream->runtime->hw.fifo_size;  in snd_pcm_lib_ioctl_fifo_size()
1733 	if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_FIFO_IN_FRAMES)) {  in snd_pcm_lib_ioctl_fifo_size()
1782 	struct snd_pcm_runtime *runtime;  in snd_pcm_period_elapsed()  local
1791 	runtime = substream->runtime;  in snd_pcm_period_elapsed()
1802 	kill_fasync(&runtime->fasync, SIGIO, POLL_IN);  in snd_pcm_period_elapsed()
1817 	struct snd_pcm_runtime *runtime = substream->runtime;  in wait_for_avail()  local
1826 	add_wait_queue(&runtime->tsleep, &wait);  in wait_for_avail()
1828 	if (runtime->no_period_wakeup)  in wait_for_avail()
1837 			if (runtime->rate) {  in wait_for_avail()
1838 				long t = runtime->period_size * 2 /  in wait_for_avail()
1839 					 runtime->rate;  in wait_for_avail()
1860 		if (avail >= runtime->twake)  in wait_for_avail()
1868 		switch (runtime->status->state) {  in wait_for_avail()
1899 	remove_wait_queue(&runtime->tsleep, &wait);  in wait_for_avail()
1912 static void *get_dma_ptr(struct snd_pcm_runtime *runtime,  in get_dma_ptr()  argument
1915 	return runtime->dma_area + hwoff +  in get_dma_ptr()
1916 		channel * (runtime->dma_bytes / runtime->channels);  in get_dma_ptr()
1924 	if (copy_from_user(get_dma_ptr(substream->runtime, channel, hwoff),  in default_write_copy()
1935 	memcpy(get_dma_ptr(substream->runtime, channel, hwoff), buf, bytes);  in default_write_copy_kernel()
1946 	struct snd_pcm_runtime *runtime = substream->runtime;  in fill_silence()  local
1954 	snd_pcm_format_set_silence(runtime->format,  in fill_silence()
1955 				   get_dma_ptr(runtime, channel, hwoff),  in fill_silence()
1956 				   bytes_to_samples(runtime, bytes));  in fill_silence()
1966 			 get_dma_ptr(substream->runtime, channel, hwoff),  in default_read_copy()
1977 	memcpy(buf, get_dma_ptr(substream->runtime, channel, hwoff), bytes);  in default_read_copy_kernel()
1990 	struct snd_pcm_runtime *runtime = substream->runtime;  in interleaved_copy()  local
1993 	hwoff = frames_to_bytes(runtime, hwoff);  in interleaved_copy()
1994 	off = frames_to_bytes(runtime, off);  in interleaved_copy()
1995 	frames = frames_to_bytes(runtime, frames);  in interleaved_copy()
2008 	struct snd_pcm_runtime *runtime = substream->runtime;  in noninterleaved_copy()  local
2009 	int channels = runtime->channels;  in noninterleaved_copy()
2017 	off = samples_to_bytes(runtime, off);  in noninterleaved_copy()
2018 	frames = samples_to_bytes(runtime, frames);  in noninterleaved_copy()
2019 	hwoff = samples_to_bytes(runtime, hwoff);  in noninterleaved_copy()
2038 	if (substream->runtime->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED ||  in fill_silence_frames()
2039 	    substream->runtime->access == SNDRV_PCM_ACCESS_MMAP_INTERLEAVED)  in fill_silence_frames()
2050 	struct snd_pcm_runtime *runtime;  in pcm_sanity_check()  local
2053 	runtime = substream->runtime;  in pcm_sanity_check()
2054 	if (snd_BUG_ON(!substream->ops->copy_user && !runtime->dma_area))  in pcm_sanity_check()
2056 	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)  in pcm_sanity_check()
2061 static int pcm_accessible_state(struct snd_pcm_runtime *runtime)  in pcm_accessible_state()  argument
2063 	switch (runtime->status->state) {  in pcm_accessible_state()
2083 	struct snd_pcm_runtime *runtime = substream->runtime;  in pcm_lib_apply_appl_ptr()  local
2084 	snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;  in pcm_lib_apply_appl_ptr()
2090 	runtime->control->appl_ptr = appl_ptr;  in pcm_lib_apply_appl_ptr()
2094 			runtime->control->appl_ptr = old_appl_ptr;  in pcm_lib_apply_appl_ptr()
2109 	struct snd_pcm_runtime *runtime = substream->runtime;  in __snd_pcm_lib_xfer()  local
2125 		if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&  in __snd_pcm_lib_xfer()
2126 		    runtime->channels > 1)  in __snd_pcm_lib_xfer()
2130 		if (runtime->access != SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)  in __snd_pcm_lib_xfer()
2160 	err = pcm_accessible_state(runtime);  in __snd_pcm_lib_xfer()
2164 	runtime->twake = runtime->control->avail_min ? : 1;  in __snd_pcm_lib_xfer()
2165 	if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)  in __snd_pcm_lib_xfer()
2173 	    runtime->status->state == SNDRV_PCM_STATE_PREPARED &&  in __snd_pcm_lib_xfer()
2174 	    size >= runtime->start_threshold) {  in __snd_pcm_lib_xfer()
2187 			    runtime->status->state == SNDRV_PCM_STATE_DRAINING) {  in __snd_pcm_lib_xfer()
2195 			runtime->twake = min_t(snd_pcm_uframes_t, size,  in __snd_pcm_lib_xfer()
2196 					runtime->control->avail_min ? : 1);  in __snd_pcm_lib_xfer()
2204 		appl_ptr = READ_ONCE(runtime->control->appl_ptr);  in __snd_pcm_lib_xfer()
2205 		appl_ofs = appl_ptr % runtime->buffer_size;  in __snd_pcm_lib_xfer()
2206 		cont = runtime->buffer_size - appl_ofs;  in __snd_pcm_lib_xfer()
2219 		err = pcm_accessible_state(runtime);  in __snd_pcm_lib_xfer()
2223 		if (appl_ptr >= runtime->boundary)  in __snd_pcm_lib_xfer()
2224 			appl_ptr -= runtime->boundary;  in __snd_pcm_lib_xfer()
2234 		    runtime->status->state == SNDRV_PCM_STATE_PREPARED &&  in __snd_pcm_lib_xfer()
2235 		    snd_pcm_playback_hw_avail(runtime) >= (snd_pcm_sframes_t)runtime->start_threshold) {  in __snd_pcm_lib_xfer()
2242 	runtime->twake = 0;  in __snd_pcm_lib_xfer()
2244 		snd_pcm_update_state(substream, runtime);  in __snd_pcm_lib_xfer()
2336 	if (!substream->runtime)  in pcm_chmap_ctl_get()
2340 		if (map->channels == substream->runtime->channels &&  in pcm_chmap_ctl_get()