diff options
| author | Lars-Peter Clausen <lars@metafoo.de> | 2014-12-29 18:43:37 +0100 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2014-12-30 16:27:47 +0100 |
| commit | 8ef9df55a72425e269575fa74cbbedec4672bdc4 (patch) | |
| tree | 26b586cdb86993462827f6558d2187e52c9669ed /sound/core | |
| parent | 19f52fae5adb7f2fd5b75251f9bd761f43a36476 (diff) | |
| download | linux-8ef9df55a72425e269575fa74cbbedec4672bdc4.tar.bz2 | |
ALSA: Add support for wildcard msbits constraints
Currently the msbits constraints requires to specify a specific sample
format width for which the constraint should be applied. But often the
number of most significant bits is not sample format specific, but rather a
absolute limit. E.g. the PCM interface might accept 32-bit and 24-bit
samples, but the DAC has a 16-bit resolution and throws away the LSBs. In
this case for both 32-bit and 24-bit format msbits should be set to 16. This
patch extends snd_pcm_hw_constraint_msbits() so that a wildcard constraint
can be setup that is applied for all formats with a sample width larger than
the specified msbits. Choosing the wildcard constraint is done by setting
the sample width parameter of the function to 0.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core')
| -rw-r--r-- | sound/core/pcm_lib.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index b0c153534a29..db05e04d0070 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1299,8 +1299,14 @@ static int snd_pcm_hw_rule_msbits(struct snd_pcm_hw_params *params, int width = l & 0xffff; unsigned int msbits = l >> 16; struct snd_interval *i = hw_param_interval(params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS); - if (snd_interval_single(i) && snd_interval_value(i) == width) + + if (!snd_interval_single(i)) + return 0; + + if ((snd_interval_value(i) == width) || + (width == 0 && snd_interval_value(i) > msbits)) params->msbits = min_not_zero(params->msbits, msbits); + return 0; } @@ -1311,6 +1317,11 @@ static int snd_pcm_hw_rule_msbits(struct snd_pcm_hw_params *params, * @width: sample bits width * @msbits: msbits width * + * This constraint will set the number of most significant bits (msbits) if a + * sample format with the specified width has been select. If width is set to 0 + * the msbits will be set for any sample format with a width larger than the + * specified msbits. + * * Return: Zero if successful, or a negative error code on failure. */ int snd_pcm_hw_constraint_msbits(struct snd_pcm_runtime *runtime, |