diff options
Diffstat (limited to 'sound/usb/format.c')
-rw-r--r-- | sound/usb/format.c | 92 |
1 files changed, 74 insertions, 18 deletions
diff --git a/sound/usb/format.c b/sound/usb/format.c index 8eccf17..30364ab 100644 --- a/sound/usb/format.c +++ b/sound/usb/format.c @@ -206,6 +206,60 @@ static int parse_audio_format_rates_v1(struct snd_usb_audio *chip, struct audiof } /* + * Helper function to walk the array of sample rate triplets reported by + * the device. The problem is that we need to parse whole array first to + * get to know how many sample rates we have to expect. + * Then fp->rate_table can be allocated and filled. + */ +static int parse_uac2_sample_rate_range(struct audioformat *fp, int nr_triplets, + const unsigned char *data) +{ + int i, nr_rates = 0; + + fp->rates = fp->rate_min = fp->rate_max = 0; + + for (i = 0; i < nr_triplets; i++) { + int min = combine_quad(&data[2 + 12 * i]); + int max = combine_quad(&data[6 + 12 * i]); + int res = combine_quad(&data[10 + 12 * i]); + int rate; + + if ((max < 0) || (min < 0) || (res < 0) || (max < min)) + continue; + + /* + * for ranges with res == 1, we announce a continuous sample + * rate range, and this function should return 0 for no further + * parsing. + */ + if (res == 1) { + fp->rate_min = min; + fp->rate_max = max; + fp->rates = SNDRV_PCM_RATE_CONTINUOUS; + return 0; + } + + for (rate = min; rate <= max; rate += res) { + if (fp->rate_table) + fp->rate_table[nr_rates] = rate; + if (!fp->rate_min || rate < fp->rate_min) + fp->rate_min = rate; + if (!fp->rate_max || rate > fp->rate_max) + fp->rate_max = rate; + fp->rates |= snd_pcm_rate_to_rate_bit(rate); + + nr_rates++; + + /* avoid endless loop */ + if (res == 0) + break; + } + } + + return nr_rates; +} + +/* * parse the format descriptor and stores the possible sample rates * on the audioformat table (audio class v2). */ @@ -215,7 +269,7 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip, { struct usb_device *dev = chip->dev; unsigned char tmp[2], *data; - int i, nr_rates, data_size, ret = 0; + int nr_triplets, data_size, ret = 0; int clock = snd_usb_clock_find_source(chip, chip->ctrl_intf, fp->clock); if (clock < 0) { @@ -237,8 +291,8 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip, goto err; } - nr_rates = (tmp[1] << 8) | tmp[0]; - data_size = 2 + 12 * nr_rates; + nr_triplets = (tmp[1] << 8) | tmp[0]; + data_size = 2 + 12 * nr_triplets; data = kzalloc(data_size, GFP_KERNEL); if (!data) { ret = -ENOMEM; @@ -259,26 +313,28 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip, goto err_free; } - fp->rate_table = kmalloc(sizeof(int) * nr_rates, GFP_KERNEL); + /* Call the triplet parser, and make sure fp->rate_table is NULL. + * We just use the return value to know how many sample rates we + * will have to deal with. */ + kfree(fp->rate_table); + fp->rate_table = NULL; + fp->nr_rates = parse_uac2_sample_rate_range(fp, nr_triplets, data); + + if (fp->nr_rates == 0) { + /* SNDRV_PCM_RATE_CONTINUOUS */ + ret = 0; + goto err_free; + } + + fp->rate_table = kmalloc(sizeof(int) * fp->nr_rates, GFP_KERNEL); if (!fp->rate_table) { ret = -ENOMEM; goto err_free; } - fp->nr_rates = 0; - fp->rate_min = fp->rate_max = 0; - - for (i = 0; i < nr_rates; i++) { - int rate = combine_quad(&data[2 + 12 * i]); - - fp->rate_table[fp->nr_rates] = rate; - if (!fp->rate_min || rate < fp->rate_min) - fp->rate_min = rate; - if (!fp->rate_max || rate > fp->rate_max) - fp->rate_max = rate; - fp->rates |= snd_pcm_rate_to_rate_bit(rate); - fp->nr_rates++; - } + /* Call the triplet parser again, but this time, fp->rate_table is + * allocated, so the rates will be stored */ + parse_uac2_sample_rate_range(fp, nr_triplets, data); err_free: kfree(data); |