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authorOlivier Moysan <olivier.moysan@st.com>2017-10-19 15:03:19 +0200
committerMark Brown <broonie@kernel.org>2017-10-21 11:16:32 +0100
commita4529d2b885747bb9393d507cd28649052d733f3 (patch)
tree6da1721497087bc09e5eafc1281bd0f116f3bcb9 /sound/soc/stm/stm32_sai_sub.c
parentd807cdfb48c4d925b269f5b0f818864766e17389 (diff)
downloadlinux-a4529d2b885747bb9393d507cd28649052d733f3.tar.bz2
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>
Diffstat (limited to 'sound/soc/stm/stm32_sai_sub.c')
-rw-r--r--sound/soc/stm/stm32_sai_sub.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/sound/soc/stm/stm32_sai_sub.c b/sound/soc/stm/stm32_sai_sub.c
index 5e66bf310351..dde8ddf9e777 100644
--- a/sound/soc/stm/stm32_sai_sub.c
+++ b/sound/soc/stm/stm32_sai_sub.c
@@ -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;