spi: respect the maximum segment size of DMA device

The device which is actually does DMA may have a limitation of the maximum
segment size. Respect this setting when preparing scatter-gather list.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 47eff8012a7715c362eb3ac3e706f8a9ea6e71c2..9e6480a2e86920c73b52a3d7239f39a9fd916665 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -702,6 +702,7 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
                       enum dma_data_direction dir)
 {
        const bool vmalloced_buf = is_vmalloc_addr(buf);
+       unsigned int max_seg_size = dma_get_max_seg_size(dev);
        int desc_len;
        int sgs;
        struct page *vm_page;
@@ -710,10 +711,10 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
        int i, ret;
 
        if (vmalloced_buf) {
-               desc_len = PAGE_SIZE;
+               desc_len = min_t(int, max_seg_size, PAGE_SIZE);
                sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
        } else {
-               desc_len = master->max_dma_len;
+               desc_len = min_t(int, max_seg_size, master->max_dma_len);
                sgs = DIV_ROUND_UP(len, desc_len);
        }
 
@@ -739,7 +740,6 @@ static int spi_map_buf(struct spi_master *master, struct device *dev,
                        sg_set_buf(&sgt->sgl[i], sg_buf, min);
                }
 
-
                buf += min;
                len -= min;
        }