[PATCH v5 10/10] ASoC: rockchip_i2s: modify DMA max burst to 1

Shawn Lin shawn.lin at rock-chips.com
Sun Sep 13 16:49:42 PDT 2015

From: Yiwei Cai <cain.cai at rock-chips.com>

Test with command -
arecord -D hw:0,0 /tmp/a.wav, there are the error dump:
dma-pl330 ffb20000.dma-controller: fill_queue:2251 Bad Desc(7)

This error is happening when no a multiple of burst size * burst
length are coming in. The root cause is pl330 dma controller on
Rockchips' platform cannot support DMAFLUSHP instruction which make
dma to flush the req of non-aligned or non-multiple of what we set
before. The saftest way is to set dma max burst to 1.

Signed-off-by: Yiwei Cai <cain.cai at rock-chips.com>
Fixes: 4495c89fc ("ASoC: add driver for Rockchip RK3xxx I2S")
Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
cc: Addy Ke <addy.ke at rock-chips.com>
cc: Jianqun Xu <xjq at rock-chips.com>
cc: Heiko Stuebner <heiko at sntech.de>
cc: Olof Johansson <olof at lixom.net>
cc: Doug Anderson <dianders at chromium.org>
cc: Sonny Rao <sonnyrao at chromium.org>
cc: Mark Brown <broonie at kernel.org>


Changes in v5:
- use switch statement for dma_quirk's manipulation

Changes in v4: None
Changes in v3: None
Changes in v2: None
Changes in v1: None

 sound/soc/rockchip/rockchip_i2s.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index acb5be5..543d0c0 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -23,6 +23,8 @@
 #define DRV_NAME "rockchip-i2s"
+#define ROCKCHIP_I2S_BROKEN_BURST_LEN (1<<0) /* broken burst len */
 struct rk_i2s_dev {
 	struct device *dev;
@@ -418,6 +420,7 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 	struct rk_i2s_dev *i2s;
 	struct resource *res;
 	void __iomem *regs;
+	int dma_quirk;
 	int ret;
 	i2s = devm_kzalloc(&pdev->dev, sizeof(*i2s), GFP_KERNEL);
@@ -489,6 +492,24 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 		goto err_pcm_register;
+	dma_quirk = snd_dmaengine_pcm_get_quirks(&pdev->dev);
+	switch (dma_quirk) {
+		/*
+		 * Unfortunately, we find broken burst len here,
+		 * just have to limit maxburst to ONE in order to avoid
+		 * non-multiple burst len access fail the dmaengine if
+		 * it can't support flush peripheral function.
+		 */
+		i2s->playback_dma_data.maxburst = 1;
+		i2s->capture_dma_data.maxburst = 1;
+		break;
+	default:
+		dev_info(&pdev->dev, "Default no dma_quirk!\n");
+		break;
+	}
 	return 0;

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