From 8ef9df55a72425e269575fa74cbbedec4672bdc4 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Mon, 29 Dec 2014 18:43:37 +0100 Subject: [PATCH] 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 Signed-off-by: Takashi Iwai --- sound/core/pcm_lib.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) 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, -- 2.20.1