From 3528f27a5d4ac299e2d8cbe7297c1e9edd601ee6 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Mon, 11 Jun 2012 20:11:42 +0200 Subject: ASoC: dmaengine-pcm: Add support for querying stream position from DMA driver Currently the sound dmaengine pcm helper functions implement the pcm_pointer callback by trying to count the number of elapsed periods. This is done by advancing the stream position in the dmaengine callback by one period. Unfortunately there is no guarantee that the callback will be called for each elapsed period. It may be possible that under high system load it is only called once for multiple elapsed periods. This patch addresses the issue by implementing support for querying the current stream position directly from the dmaengine driver. Since not all dmaengine drivers support reporting the stream position yet the old period counting implementation is kept for now. Furthermore the new mechanism allows to report the stream position with a sub-period granularity, given that the dmaengine driver supports this. Signed-off-by: Lars-Peter Clausen Acked-by: Vinod Koul Signed-off-by: Mark Brown --- sound/soc/soc-dmaengine-pcm.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) (limited to 'sound/soc/soc-dmaengine-pcm.c') diff --git a/sound/soc/soc-dmaengine-pcm.c b/sound/soc/soc-dmaengine-pcm.c index 7c0877e3731c..2995334d8000 100644 --- a/sound/soc/soc-dmaengine-pcm.c +++ b/sound/soc/soc-dmaengine-pcm.c @@ -30,6 +30,7 @@ struct dmaengine_pcm_runtime_data { struct dma_chan *dma_chan; + dma_cookie_t cookie; unsigned int pos; @@ -153,7 +154,7 @@ static int dmaengine_pcm_prepare_and_submit(struct snd_pcm_substream *substream) desc->callback = dmaengine_pcm_dma_complete; desc->callback_param = substream; - dmaengine_submit(desc); + prtd->cookie = dmaengine_submit(desc); return 0; } @@ -213,6 +214,32 @@ snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream } EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer_no_residue); +/** + * snd_dmaengine_pcm_pointer - dmaengine based PCM pointer implementation + * @substream: PCM substream + * + * This function can be used as the PCM pointer callback for dmaengine based PCM + * driver implementations. + */ +snd_pcm_uframes_t snd_dmaengine_pcm_pointer(struct snd_pcm_substream *substream) +{ + struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream); + struct dma_tx_state state; + enum dma_status status; + unsigned int buf_size; + unsigned int pos = 0; + + status = dmaengine_tx_status(prtd->dma_chan, prtd->cookie, &state); + if (status == DMA_IN_PROGRESS || status == DMA_PAUSED) { + buf_size = snd_pcm_lib_buffer_bytes(substream); + if (state.residue > 0 && state.residue <= buf_size) + pos = buf_size - state.residue; + } + + return bytes_to_frames(substream->runtime, pos); +} +EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer); + static int dmaengine_pcm_request_channel(struct dmaengine_pcm_runtime_data *prtd, dma_filter_fn filter_fn, void *filter_data) { -- cgit v1.2.3