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ASoC: stm32: sai: Fix DMA burst size 

Set best burst size tradeoff for 8, 16, 32 bits transfers.

Signed-off-by: olivier moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Olivier Moysan 2017-10-19 15:03:19 +02:00 committed by Mark Brown
parent d807cdfb48
commit a4529d2b88
1 changed files with 13 additions and 8 deletions
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21
sound/soc/stm/stm32_sai_sub.c
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@ -446,12 +446,16 @@ static int stm32_sai_set_config(struct snd_soc_dai *cpu_dai,
{
struct stm32_sai_sub_data *sai = snd_soc_dai_get_drvdata(cpu_dai);
int cr1, cr1_mask, ret;
int fth = STM_SAI_FIFO_TH_HALF;
/* FIFO config */
/*
* DMA bursts increment is set to 4 words.
* SAI fifo threshold is set to half fifo, to keep enough space
* for DMA incoming bursts.
*/
regmap_update_bits(sai->regmap, STM_SAI_CR2_REGX,
SAI_XCR2_FFLUSH | SAI_XCR2_FTH_MASK,
SAI_XCR2_FFLUSH | SAI_XCR2_FTH_SET(fth));
SAI_XCR2_FFLUSH |
SAI_XCR2_FTH_SET(STM_SAI_FIFO_TH_HALF));
/* Mode, data format and channel config */
cr1 = SAI_XCR1_PRTCFG_SET(SAI_FREE_PROTOCOL);
@ -485,10 +489,6 @@ static int stm32_sai_set_config(struct snd_soc_dai *cpu_dai,
return ret;
}
/* DMA config */
sai->dma_params.maxburst = STM_SAI_FIFO_SIZE * fth / sizeof(u32);
snd_soc_dai_set_dma_data(cpu_dai, substream, (void *)&sai->dma_params);
return 0;
}
@ -731,7 +731,12 @@ static int stm32_sai_dai_probe(struct snd_soc_dai *cpu_dai)
struct stm32_sai_sub_data *sai = dev_get_drvdata(cpu_dai->dev);
sai->dma_params.addr = (dma_addr_t)(sai->phys_addr + STM_SAI_DR_REGX);
sai->dma_params.maxburst = 1;
/*
* DMA supports 4, 8 or 16 burst sizes. Burst size 4 is the best choice,
* as it allows bytes, half-word and words transfers. (See DMA fifos
* constraints).
*/
sai->dma_params.maxburst = 4;
/* Buswidth will be set by framework at runtime */
sai->dma_params.addr_width = DMA_SLAVE_BUSWIDTH_UNDEFINED;