MX28: SPI: Fix the DMA DCache race condition

[karo-tx-uboot.git] / drivers / spi / mxs_spi.c

diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index 168dbe497e6dc73f70cdd38a3c98030e32b6dbe8..c3997070019f7686b0bfcea78187a964ee3f2c64 100644 (file)
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -224,6 +224,7 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave,
        struct mxs_dma_desc *dp;
        uint32_t ctrl0;
        uint32_t cache_data_count;
+       const uint32_t dstart = (uint32_t)data;
        int dmach;
        int tl;
 
@@ -246,10 +247,12 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave,
        else
                cache_data_count = length;
 
+       /* Flush data to DRAM so DMA can pick them up */
        if (write)
-               /* Flush data to DRAM so DMA can pick them up */
-               flush_dcache_range((uint32_t)data,
-                       (uint32_t)(data + cache_data_count));
+               flush_dcache_range(dstart, dstart + cache_data_count);
+
+       /* Invalidate the area, so no writeback into the RAM races with DMA */
+       invalidate_dcache_range(dstart, dstart + cache_data_count);
 
        dmach = MXS_DMA_CHANNEL_AHB_APBH_SSP0 + slave->slave.bus;
 
@@ -310,10 +313,8 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave,
                return -EINVAL;
 
        /* The data arrived into DRAM, invalidate cache over them */
-       if (!write) {
-               invalidate_dcache_range((uint32_t)data,
-                       (uint32_t)(data + cache_data_count));
-       }
+       if (!write)
+               invalidate_dcache_range(dstart, dstart + cache_data_count);
 
        return 0;
 }