[PATCH v3 8/9] spi: rockchip: modify DMA max burst to 1

[Shawn Lin]

From: Addy Ke <addy.ke at rock-chips.com>

Generic 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 need. That will cause an unrecoverable
dma bus error. The saftest way is to set dma max burst to 1.

Signed-off-by: Addy ke <addy.ke at rock-chips.com>
Fixes: 64e36824b32b06 ("spi/rockchip: add driver for Rockchip...")
Signed-off-by: Shawn Lin <shawn.lin 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

 drivers/spi/spi-rockchip.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 68e7efe..3748ca5 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -199,6 +199,8 @@ struct rockchip_spi {
 	struct sg_table rx_sg;
 	struct rockchip_spi_dma_data dma_rx;
 	struct rockchip_spi_dma_data dma_tx;
+	int quirk;
+#define ROCKCHIP_SPI_BORKEN_BURST_LEN (1<<0) /* broken burst len*/
 };
 
 static inline void spi_enable_chip(struct rockchip_spi *rs, int enable)
@@ -449,7 +451,10 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		rxconf.direction = rs->dma_rx.direction;
 		rxconf.src_addr = rs->dma_rx.addr;
 		rxconf.src_addr_width = rs->n_bytes;
-		rxconf.src_maxburst = rs->n_bytes;
+		if (rs->quirk & ROCKCHIP_SPI_BORKEN_BURST_LEN)
+			rxconf.src_maxburst = 1;
+		else
+			rxconf.src_maxburst = rs->n_bytes;
 		dmaengine_slave_config(rs->dma_rx.ch, &rxconf);
 
 		rxdesc = dmaengine_prep_slave_sg(
@@ -466,7 +471,10 @@ static void rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		txconf.direction = rs->dma_tx.direction;
 		txconf.dst_addr = rs->dma_tx.addr;
 		txconf.dst_addr_width = rs->n_bytes;
-		txconf.dst_maxburst = rs->n_bytes;
+		if (rs->quirk & ROCKCHIP_SPI_BORKEN_BURST_LEN)
+			txconf.dst_maxburst = 1;
+		else
+			txconf.dst_maxburst = rs->n_bytes;
 		dmaengine_slave_config(rs->dma_tx.ch, &txconf);
 
 		txdesc = dmaengine_prep_slave_sg(
@@ -699,6 +707,10 @@ static int rockchip_spi_probe(struct platform_device *pdev)
 		goto err_get_fifo_len;
 	}
 
+	if (of_property_read_bool(pdev->dev.of_node,
+				  "rockchip,spi-broken-burst-len"))
+		rs->quirk |= ROCKCHIP_SPI_BORKEN_BURST_LEN;
+
 	spin_lock_init(&rs->lock);
 
 	pm_runtime_set_active(&pdev->dev);
-- 
2.3.7