mmc: sdhci: fix missing cache invalidation after reading by DMA

This driver currently performs cache operation before the DMA start,
but does nothing after the DMA completion.

When reading data by DMA, the cache invalidation is needed also after
finishing the DMA transfer. Otherwise, the CPU might read data from
the cache instead of from the main memory when speculative memory read
or memory prefetch occurs.

Instead of calling the cache operation directly, this commit adds
dma_unmap_single(), which performs cache invalidation internally,
but drivers do not need which operation is being run.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 77a88bc043e40be41f4abf7da8f5ca4e7f02fc08..9b7c5f8f684ff63949694beac06bbd310fd0a6e7 100644 (file)
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -215,6 +215,10 @@ static int sdhci_transfer_data(struct sdhci_host *host, struct mmc_data *data)
                        return -ETIMEDOUT;
                }
        } while (!(stat & SDHCI_INT_DATA_END));
+
+       dma_unmap_single(host->start_addr, data->blocks * data->blocksize,
+                        mmc_get_dma_dir(data));
+
        return 0;
 }