[PATCH 4.4 248/312] spi: rockchip: modify DMA max burst to 1

[Greg Kroah-Hartman]

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

commit 80abf8880cc6e1594c11b7c417f22dde60e25312 upstream.

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...@rock-chips.com>
Fixes: 64e36824b32b06 ("spi/rockchip: add driver for Rockchip...")
Signed-off-by: Shawn Lin <shawn....@rock-chips.com>
cc: Heiko Stuebner <he...@sntech.de>
cc: Olof Johansson <o...@lixom.net>
cc: Doug Anderson <diand...@chromium.org>
cc: Sonny Rao <sonny...@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

Acked-by: Mark Brown <broo...@kernel.org>
Signed-off-by: Caesar Wang <w...@rock-chips.com>
Signed-off-by: Vinod Koul <vinod.k...@intel.com>

---
 drivers/spi/spi-rockchip.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- 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)
@@ -457,7 +458,10 @@ static void rockchip_spi_prepare_dma(str
                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(
@@ -474,7 +478,10 @@ static void rockchip_spi_prepare_dma(str
                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(
@@ -738,6 +745,7 @@ static int rockchip_spi_probe(struct pla
        }
 
        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;