spi: rockchip: modify DMA max burst to 1

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@rock-chips.com>
Fixes: 64e36824b32b06 ("spi/rockchip: add driver for Rockchip...")
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
cc: Heiko Stuebner <heiko@sntech.de>
cc: Olof Johansson <olof@lixom.net>
cc: Doug Anderson <dianders@chromium.org>
cc: Sonny Rao <sonnyrao@chromium.org>

Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 79a8bc4f6cec9e32ec9c78627a2e68fc85ab5e12..aa9561f586ab9a047410652f811ad4ebdffbc7ca 100644 (file)
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -199,6 +199,7 @@ struct rockchip_spi {
        struct sg_table rx_sg;
        struct rockchip_spi_dma_data dma_rx;
        struct rockchip_spi_dma_data dma_tx;
+       struct dma_slave_caps dma_caps;
 };
 
 static inline void spi_enable_chip(struct rockchip_spi *rs, int enable)
@@ -449,7 +450,10 @@ 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->dma_caps.max_burst > 4)
+                       rxconf.src_maxburst = 4;
+               else
+                       rxconf.src_maxburst = 1;
                dmaengine_slave_config(rs->dma_rx.ch, &rxconf);
 
                rxdesc = dmaengine_prep_slave_sg(
@@ -466,7 +470,10 @@ 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->dma_caps.max_burst > 4)
+                       txconf.dst_maxburst = 4;
+               else
+                       txconf.dst_maxburst = 1;
                dmaengine_slave_config(rs->dma_tx.ch, &txconf);
 
                txdesc = dmaengine_prep_slave_sg(
@@ -730,6 +737,7 @@ static int rockchip_spi_probe(struct platform_device *pdev)
        }
 
        if (rs->dma_tx.ch && rs->dma_rx.ch) {
+               dma_get_slave_caps(rs->dma_rx.ch, &(rs->dma_caps));
                rs->dma_tx.addr = (dma_addr_t)(mem->start + ROCKCHIP_SPI_TXDR);
                rs->dma_rx.addr = (dma_addr_t)(mem->start + ROCKCHIP_SPI_RXDR);
                rs->dma_tx.direction = DMA_MEM_TO_DEV;