mmc: sdhci: further fix for DMA unmapping in sdhci_post_req()

sdhci_post_req() exists to unmap a previously mapped but already
finished request, while the next request is in progress.  However, the
state of the SDHCI_REQ_USE_DMA flag depends on the last submitted
request.

This means we can end up clearing the flag due to a quirk, which then
means that sdhci_post_req() fails to unmap the DMA buffer, potentially
leading to data corruption.

We can safely ignore the SDHCI_REQ_USE_DMA here, as testing
data->host_cookie is entirely sufficient.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[ Re-based to apply as a separate fix ]
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v4.5+
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 97e5f40..6fe0e78 100644 (file)
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2084,14 +2084,13 @@ static void sdhci_post_req(struct mmc_host *mmc, struct mmc_request *mrq,
        struct sdhci_host *host = mmc_priv(mmc);
        struct mmc_data *data = mrq->data;
 
-       if (host->flags & SDHCI_REQ_USE_DMA) {
-               if (data->host_cookie == COOKIE_GIVEN ||
-                               data->host_cookie == COOKIE_MAPPED)
-                       dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
-                                        data->flags & MMC_DATA_WRITE ?
-                                        DMA_TO_DEVICE : DMA_FROM_DEVICE);
-               data->host_cookie = COOKIE_UNMAPPED;
-       }
+       if (data->host_cookie == COOKIE_GIVEN ||
+           data->host_cookie == COOKIE_MAPPED)
+               dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
+                            data->flags & MMC_DATA_WRITE ?
+                              DMA_TO_DEVICE : DMA_FROM_DEVICE);
+
+       data->host_cookie = COOKIE_UNMAPPED;
 }
 
 static int sdhci_pre_dma_transfer(struct sdhci_host *host,