On Wed, Nov 10, 2010 at 5:00 PM, Jaroslav Kysela <perex@xxxxxxxx> wrote:
> On Wed, 10 Nov 2010, Manu Abraham wrote:
>
>> Ok, so period should be the interval at which an IRQ is expected.
>> ie, if i set a buffer size for 40mS, the period should be 40, I guess.
>>
>> That said, what should be a recommended value for period ? If hardware
>> needs to generate an IRQ at the end of each period ?
>
> It's good to allow the lowledevel driver to pass all possible period sizes
> to the user space. The application does decision how many wakeups expects.
Ok, I adapted it to look thus,
static struct snd_pcm_hardware saa7231_capture_info = {
.info = (SNDRV_PCM_INFO_MMAP |
SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_MMAP_VALID),
.formats = (SNDRV_PCM_FMTBIT_S16_LE |
SNDRV_PCM_FMTBIT_S16_BE |
SNDRV_PCM_FMTBIT_S8 |
SNDRV_PCM_FMTBIT_U8 |
SNDRV_PCM_FMTBIT_U16_LE |
SNDRV_PCM_FMTBIT_U16_BE),
.rates = SNDRV_PCM_RATE_32000,
.rate_min = 32000,
.rate_max = 48000,
.channels_min = 2,
.channels_max = 2,
.buffer_bytes_max = 512 * 4096,
#if 0
.period_bytes_min = 192,
.period_bytes_max = 1536,
.periods_min = 2,
.periods_max = 1024,
#endif
.period_bytes_min = 1920, /* 10mS @ 48khz */
.period_bytes_max = 768000, /* 4S @ 48kHz */
.periods_min = 10, /* 10mS */
.periods_max = 4000000, /* 4S */
};
/*
* 10mS Buffer lengths
* @48kHz 1920 bytes
* @44.1kHz 1764 bytes
* @32kHz 1280 bytes
*
*
* period min = 10mS @48k: 1920 bytes @44.1k: 1764 bytes @32k: 1280 bytes
* period max = 1S @48k:192000 bytes @44.1k:176400 bytes @32k:128000 bytes
* period = 4S @48k:768000 bytes @44.1k:705600 bytes @32k:512000 bytes
*/
static int saa7231_capture_open(struct snd_pcm_substream *pcm)
{
struct saa7231_audio *audio = snd_pcm_substream_chip(pcm);
struct snd_pcm_runtime *rt = pcm->runtime;
struct saa7231_dev *saa7231 = audio->saa7231;
int err;
dprintk(SAA7231_DEBUG, 1, "()");
rt->hw = saa7231_capture_info;
snd_pcm_hw_constraint_list(rt, 0, SNDRV_PCM_HW_PARAM_RATE,
&hw_constraint_rates);
err = snd_pcm_hw_constraint_integer(rt, SNDRV_PCM_HW_PARAM_PERIODS);
if (err < 0) {
dprintk(SAA7231_ERROR, 1, "snd_pcm_hw_constraint_integer() failed.
ret=%d", err);
return err;
}
err = snd_pcm_hw_constraint_minmax(rt,
SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 10, 4000000);
if (err < 0) {
dprintk(SAA7231_ERROR, 1, "snd_pcm_hw_constraint_minmax() failed.
ret=%d", err);
return err;
}
err = snd_pcm_hw_constraint_minmax(rt,
SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 1920, 768000);
if (err < 0) {
dprintk(SAA7231_ERROR, 1, "snd_pcm_hw_constraint_minmax() failed.
ret=%d", err);
return err;
}
return 0;
}
/*
* saa7231_hw_params()
*
* This callback is called when the hardware parameter (hw_params) is setup
* by the application, ie., once when the buffer size, the period size,
* the format etc are defined for the PCM substream.
*/
static int saa7231_hw_params(struct snd_pcm_substream *pcm, struct
snd_pcm_hw_params *params)
{
struct saa7231_audio *audio = snd_pcm_substream_chip(pcm);
struct saa7231_dev *saa7231 = audio->saa7231;
struct snd_pcm_runtime *rt = pcm->runtime;
struct saa7231_dmabuf *buffer;
struct saa7231_stream *stream;
struct saa7231_dmabuf *dmabuf;
struct page **ptable;
void *mem;
void *dma_area;
int i, j, pages, bytes, periods, bufsiz, pt_size;
dprintk(SAA7231_DEBUG, 1, "DEBUG: ()");
periods = params_periods(params);
bytes = params_period_bytes(params);
bufsiz = periods * bytes;
dprintk(SAA7231_DEBUG, 1, "bufsiz=%d periods=%d bytes=%d",
bufsiz,
periods,
bytes);
pages = bufsiz / PAGE_SIZE;
/* enable stream */
/* initializing 8 buffer with "pages" pages each .. */
stream = saa7231_stream_init(saa7231, AUDIO_CAPTURE, ADAPTER_INT, 0, pages);
if (!stream) {
dprintk(SAA7231_ERROR, 1, "ERROR: Registering stream");
return -ENOMEM;
}
audio->stream = stream;
buffer = stream->dmabuf;
saa7231_add_irqevent(saa7231, 43, SAA7231_EDGE_RISING,
saa7231_audio_evhandler, "AS2D_AVIS");
dprintk(SAA7231_DEBUG, 1, "Mapping %d buffers with %d pages each",
XS2D_BUFFERS, pages);
/*
* For a single DMA buffer:
* each page takes a u64 size in a page table
* number of entries a single page can hold = PAGE_SIZE / entry size
* ie entries.max = PAGE_SIZE / 8 => 4096/8 = 512
* Now, we have entries.req = 7 ("pages") per buffer
*
* For all in XS2D_BUFFERS:
* page table should be large enough to hold all the pages in each DMA buffer
* total number of pages = pages * XS2D_BUFFERS
* max buffers that we need to consider = 512 * 8, this needs 8 pages
for a page table
*
* On a general note, we can calculate pages for page table as
* page_table_size = total_pages / 512, with a minimum of a single page
*/
#define MAX_ENTRIES_PER_PAGE (PAGE_SIZE / 8)
pt_size = (pages * XS2D_BUFFERS) / MAX_ENTRIES_PER_PAGE;
/* minimum 1 page required for the table */
if (pt_size < 1)
pt_size = 1;
dprintk(SAA7231_DEBUG, 1, "Page Table array size=%d", pt_size);
ptable = kzalloc((sizeof (struct page) * pt_size), GFP_KERNEL);
if (!ptable) {
dprintk(SAA7231_ERROR, 1, "ERROR: No memory to allocate virtual map");
return -ENOMEM;
}
audio->ptable = ptable;
for (i = 0; i < XS2D_BUFFERS; i ++) {
dmabuf = &buffer[i];
mem = dmabuf->vmalloc;
for (j = 0; j < pages; j++)
ptable[j] = virt_to_page(mem);
}
#if 0
dma_area = vmap(ptable, (pages * XS2D_BUFFERS), VM_MAP, PAGE_KERNEL);
rt->dma_area = dma_area;
rt->dma_bytes = XS2D_BUFFERS * pages * SAA7231_PAGE_SIZE;
rt->dma_addr = 0;
#endif
return 0;
}
also after vmap(), crazy thing was that uncommenting the above #if 0'd block,
ie with vmap() it would just crash the whole system.
Best Regards,
Manu
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