[alsa-devel] [PATCH v3 9/9] ASoC: rockchip_i2s: modify DMA max burst to 1

[Shawn Lin]

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:
[  134.899396] 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>
---

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

 sound/soc/rockchip/rockchip_i2s.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index acb5be5..5d35b2c 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -457,13 +457,19 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 		return PTR_ERR(i2s->regmap);
 	}
 
+	if (of_property_read_bool(np, "rockchip,i2s-broken-burst-len")) {
+		i2s->playback_dma_data.maxburst = 1;
+		i2s->capture_dma_data.maxburst = 1;
+	} else {
+		i2s->playback_dma_data.maxburst = 4;
+		i2s->capture_dma_data.maxburst = 4;
+	}
+
 	i2s->playback_dma_data.addr = res->start + I2S_TXDR;
 	i2s->playback_dma_data.addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-	i2s->playback_dma_data.maxburst = 4;
 
 	i2s->capture_dma_data.addr = res->start + I2S_RXDR;
 	i2s->capture_dma_data.addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-	i2s->capture_dma_data.maxburst = 4;
 
 	i2s->dev = &pdev->dev;
 	dev_set_drvdata(&pdev->dev, i2s);
-- 
2.3.7