[PATCH] ASoC: soc-generic-dmaengine-pcm: set period_bytes_min based on maxburst
In dmaengine_pcm_set_runtime_hwparams() period_bytes_min is hardcoded to 256. For some applications that may be too big. This patch changes that to calculate the value based on dma_data->maxburst. The correct value would be maxburst multiplied by the address width of the hardware FIFO. Unfortunately the address width is dynamically calculated based on the stream parameters and is not known at open time, so the worst case is chosen here which is 8 bytes, the maximum that is supported by dmaengine drivers. Not all drivers may set a maxburst value, so we fall back to the previously used hardcoded value of 256 bytes.
Signed-off-by: Sascha Hauer s.hauer@pengutronix.de --- sound/soc/soc-generic-dmaengine-pcm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index 99253de29a74e..734d46b9783f7 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -122,7 +122,9 @@ dmaengine_pcm_set_runtime_hwparams(struct snd_soc_component *component, SNDRV_PCM_INFO_INTERLEAVED; hw.periods_min = 2; hw.periods_max = UINT_MAX; - hw.period_bytes_min = 256; + hw.period_bytes_min = dma_data->maxburst * DMA_SLAVE_BUSWIDTH_8_BYTES; + if (!hw.period_bytes_min) + hw.period_bytes_min = 256; hw.period_bytes_max = dma_get_max_seg_size(dma_dev); hw.buffer_bytes_max = SIZE_MAX; hw.fifo_size = dma_data->fifo_size;
On Tue, 1 Mar 2022 12:34:46 +0100, Sascha Hauer wrote:
In dmaengine_pcm_set_runtime_hwparams() period_bytes_min is hardcoded to 256. For some applications that may be too big. This patch changes that to calculate the value based on dma_data->maxburst. The correct value would be maxburst multiplied by the address width of the hardware FIFO. Unfortunately the address width is dynamically calculated based on the stream parameters and is not known at open time, so the worst case is chosen here which is 8 bytes, the maximum that is supported by dmaengine drivers. Not all drivers may set a maxburst value, so we fall back to the previously used hardcoded value of 256 bytes.
[...]
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next
Thanks!
[1/1] ASoC: soc-generic-dmaengine-pcm: set period_bytes_min based on maxburst commit: 300689fb04b3f23c1ac1abfe960b48ec414df597
All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.
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Thanks, Mark
participants (2)
-
Mark Brown -
Sascha Hauer