From 6984992bf0520a07b931124d33f46b46437f6e1c Mon Sep 17 00:00:00 2001 From: Jarkko Nikula Date: Fri, 27 Mar 2009 15:32:01 +0200 Subject: [PATCH] ASoC: OMAP: Set minimum buffer size constraint for McBSP2 in OMAP3 McBSP2 in OMAP3 has 1 ksample (1k x 32 bit) internal FIFO. During initial playback startup, this FIFO is keeping the DMA request active until the FIFO is full. So now if ALSA buffer size is smaller, DMA is looping around it while filling up the HW FIFO, generating burst of interrupts as well and SW doesn't have any change to fill enough data. Signed-off-by: Jarkko Nikula Signed-off-by: Mark Brown --- sound/soc/omap/omap-mcbsp.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c index d6882be33452..9c09b94f0cf8 100644 --- a/sound/soc/omap/omap-mcbsp.c +++ b/sound/soc/omap/omap-mcbsp.c @@ -146,6 +146,17 @@ static int omap_mcbsp_dai_startup(struct snd_pcm_substream *substream, struct omap_mcbsp_data *mcbsp_data = to_mcbsp(cpu_dai->private_data); int err = 0; + if (cpu_is_omap343x() && mcbsp_data->bus_id == 1) { + /* + * McBSP2 in OMAP3 has 1024 * 32-bit internal audio buffer. + * Set constraint for minimum buffer size to the same than FIFO + * size in order to avoid underruns in playback startup because + * HW is keeping the DMA request active until FIFO is filled. + */ + snd_pcm_hw_constraint_minmax(substream->runtime, + SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 4096, UINT_MAX); + } + if (!cpu_dai->active) err = omap_mcbsp_request(mcbsp_data->bus_id); -- 2.20.1