ALSA: dummy - Fake buffer allocations
Instead of allocating the real buffers, use a fake buffer and ignore read/write in the dummy driver so that we can save the resources. For mmap, a single page (unique to the direction, though) is reused to all buffers. When the app requires to read/write the real buffers, pass fake_buffer=0 module option at loading time. This will get back to the old behavior. Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -518,6 +518,7 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
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pcm_substreams - Number of PCM substreams assigned to each PCM
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(default = 8, up to 16)
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hrtimer - Use hrtimer (=1, default) or system timer (=0)
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fake_buffer - Fake buffer allocations (default = 1)
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When multiple PCM devices are created, snd-dummy gives different
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behavior to each PCM device:
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@ -526,6 +527,12 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
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2 = interleaved without mmap
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3 = non-interleaved without mmap
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As default, snd-dummy drivers doesn't allocate the real buffers
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but either ignores read/write or mmap a single dummy page to all
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buffer pages, in order to save the resouces. If your apps need
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the read/ written buffer data to be consistent, pass fake_buffer=0
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option.
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The power-management is supported.
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Module snd-echo3g
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@ -153,6 +153,7 @@ static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
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#ifdef CONFIG_HIGH_RES_TIMERS
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static int hrtimer = 1;
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#endif
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static int fake_buffer = 1;
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module_param_array(index, int, NULL, 0444);
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MODULE_PARM_DESC(index, "Index value for dummy soundcard.");
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@ -166,6 +167,8 @@ module_param_array(pcm_substreams, int, NULL, 0444);
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MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-16) for dummy driver.");
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//module_param_array(midi_devs, int, NULL, 0444);
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//MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for dummy driver.");
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module_param(fake_buffer, bool, 0444);
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MODULE_PARM_DESC(fake_buffer, "Fake buffer allocations.");
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#ifdef CONFIG_HIGH_RES_TIMERS
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module_param(hrtimer, bool, 0644);
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MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
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@ -481,11 +484,8 @@ static int dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
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static int dummy_pcm_prepare(struct snd_pcm_substream *substream)
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{
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struct snd_pcm_runtime *runtime = substream->runtime;
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struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
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snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
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bytes_to_samples(runtime, runtime->dma_bytes));
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return dummy->timer_ops->prepare(substream);
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}
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@ -518,12 +518,19 @@ static struct snd_pcm_hardware dummy_pcm_hardware = {
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static int dummy_pcm_hw_params(struct snd_pcm_substream *substream,
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struct snd_pcm_hw_params *hw_params)
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{
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if (fake_buffer) {
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/* runtime->dma_bytes has to be set manually to allow mmap */
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substream->runtime->dma_bytes = params_buffer_bytes(hw_params);
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return 0;
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}
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return snd_pcm_lib_malloc_pages(substream,
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params_buffer_bytes(hw_params));
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}
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static int dummy_pcm_hw_free(struct snd_pcm_substream *substream)
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{
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if (fake_buffer)
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return 0;
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return snd_pcm_lib_free_pages(substream);
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}
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@ -570,6 +577,60 @@ static int dummy_pcm_close(struct snd_pcm_substream *substream)
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return 0;
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}
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/*
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* dummy buffer handling
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*/
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static void *dummy_page[2];
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static void free_fake_buffer(void)
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{
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if (fake_buffer) {
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int i;
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for (i = 0; i < 2; i++)
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if (dummy_page[i]) {
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free_page((unsigned long)dummy_page[i]);
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dummy_page[i] = NULL;
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}
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}
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}
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static int alloc_fake_buffer(void)
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{
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int i;
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if (!fake_buffer)
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return 0;
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for (i = 0; i < 2; i++) {
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dummy_page[i] = (void *)get_zeroed_page(GFP_KERNEL);
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if (!dummy_page[i]) {
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free_fake_buffer();
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return -ENOMEM;
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}
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}
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return 0;
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}
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static int dummy_pcm_copy(struct snd_pcm_substream *substream,
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int channel, snd_pcm_uframes_t pos,
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void __user *dst, snd_pcm_uframes_t count)
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{
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return 0; /* do nothing */
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}
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static int dummy_pcm_silence(struct snd_pcm_substream *substream,
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int channel, snd_pcm_uframes_t pos,
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snd_pcm_uframes_t count)
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{
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return 0; /* do nothing */
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}
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static struct page *dummy_pcm_page(struct snd_pcm_substream *substream,
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unsigned long offset)
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{
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return virt_to_page(dummy_page[substream->stream]); /* the same page */
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}
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static struct snd_pcm_ops dummy_pcm_ops = {
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.open = dummy_pcm_open,
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.close = dummy_pcm_close,
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@ -581,10 +642,25 @@ static struct snd_pcm_ops dummy_pcm_ops = {
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.pointer = dummy_pcm_pointer,
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};
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static struct snd_pcm_ops dummy_pcm_ops_no_buf = {
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.open = dummy_pcm_open,
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.close = dummy_pcm_close,
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.ioctl = snd_pcm_lib_ioctl,
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.hw_params = dummy_pcm_hw_params,
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.hw_free = dummy_pcm_hw_free,
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.prepare = dummy_pcm_prepare,
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.trigger = dummy_pcm_trigger,
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.pointer = dummy_pcm_pointer,
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.copy = dummy_pcm_copy,
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.silence = dummy_pcm_silence,
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.page = dummy_pcm_page,
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};
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static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
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int substreams)
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{
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struct snd_pcm *pcm;
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struct snd_pcm_ops *ops;
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int err;
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err = snd_pcm_new(dummy->card, "Dummy PCM", device,
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@ -592,14 +668,21 @@ static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
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if (err < 0)
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return err;
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dummy->pcm = pcm;
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snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &dummy_pcm_ops);
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snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &dummy_pcm_ops);
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if (fake_buffer)
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ops = &dummy_pcm_ops_no_buf;
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else
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ops = &dummy_pcm_ops;
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snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, ops);
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snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, ops);
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pcm->private_data = dummy;
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pcm->info_flags = 0;
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strcpy(pcm->name, "Dummy PCM");
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snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
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snd_dma_continuous_data(GFP_KERNEL),
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0, 64*1024);
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if (!fake_buffer) {
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snd_pcm_lib_preallocate_pages_for_all(pcm,
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SNDRV_DMA_TYPE_CONTINUOUS,
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snd_dma_continuous_data(GFP_KERNEL),
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0, 64*1024);
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}
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return 0;
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}
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@ -822,6 +905,7 @@ static void snd_dummy_unregister_all(void)
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for (i = 0; i < ARRAY_SIZE(devices); ++i)
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platform_device_unregister(devices[i]);
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platform_driver_unregister(&snd_dummy_driver);
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free_fake_buffer();
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}
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static int __init alsa_card_dummy_init(void)
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@ -832,6 +916,12 @@ static int __init alsa_card_dummy_init(void)
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if (err < 0)
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return err;
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err = alloc_fake_buffer();
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if (err < 0) {
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platform_driver_unregister(&snd_dummy_driver);
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return err;
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}
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cards = 0;
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for (i = 0; i < SNDRV_CARDS; i++) {
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struct platform_device *device;
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