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Commit a4529d2b authored by Olivier Moysan's avatar Olivier Moysan Committed by Mark Brown
Browse files

ASoC: stm32: sai: Fix DMA burst size 



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

Signed-off-by: default avatarolivier moysan <olivier.moysan@st.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent d807cdfb

sound/soc/stm/stm32_sai_sub.c

+13 −8
Original line number Diff line number Diff line
@@ -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;