mmc: sdhci: clean up host cookie handling

Commit d31911b9374a ("mmc: sdhci: fix dma memory leak in sdhci_pre_req()")
added a complicated method to manage the DMA map state for the data
transfer, but this complexity is not required.

There are three states:
* Unmapped
* Mapped by sdhci_pre_req()
* Mapped by sdhci_prepare_data()

sdhci_prepare_data() needs to know when the data buffers have been
successfully mapped by sdhci_pre_req(), and if so, there is no need to
map them a second time.

When we come to tear down the mapping, we want to know whether
sdhci_post_req() will be called (which is determined by sdhci_pre_req()
having been previously called) so that we can postpone the unmap
operation.

Hence, it makes sense to simply record when the successful DMA map
happened (via COOKIE_PRE_MAPPED vs COOKIE_MAPPED) rather than having
the complex mechanics involving COOKIE_MAPPED vs COOKIE_GIVEN.

If a mapping is created by sdhci_prepare_data(), we must tear it down
ourselves, without waiting for sdhci_post_req() (hence, the new
COOKIE_MAPPED case).  If the mapping is created by sdhci_pre_req()
then sdhci_post_req() is responsible for tearing the mapping down.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
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 393a1b077746311696d670c8577a9514e83c1857..16e8db00fc490a06fc31f23d62568d867de44b27 100644 (file)
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -431,12 +431,12 @@ static int sdhci_pre_dma_transfer(struct sdhci_host *host,
 {
        int sg_count;
 
-       if (data->host_cookie == COOKIE_MAPPED) {
-               data->host_cookie = COOKIE_GIVEN;
+       /*
+        * If the data buffers are already mapped, return the previous
+        * dma_map_sg() result.
+        */
+       if (data->host_cookie == COOKIE_PRE_MAPPED)
                return data->sg_count;
-       }
-
-       WARN_ON(data->host_cookie == COOKIE_GIVEN);
 
        sg_count = dma_map_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
                                data->flags & MMC_DATA_WRITE ?
@@ -2094,7 +2094,7 @@ static void sdhci_pre_req(struct mmc_host *mmc, struct mmc_request *mrq,
        mrq->data->host_cookie = COOKIE_UNMAPPED;
 
        if (host->flags & SDHCI_REQ_USE_DMA)
-               sdhci_pre_dma_transfer(host, mrq->data, COOKIE_MAPPED);
+               sdhci_pre_dma_transfer(host, mrq->data, COOKIE_PRE_MAPPED);
 }
 
 static void sdhci_card_event(struct mmc_host *mmc)

diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 0115e9907bf8243aa394de60ac959e5876d5a3a9..3bd28033dbd94aa021cbea850ffac71d763edd2b 100644 (file)
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -316,8 +316,8 @@ struct sdhci_adma2_64_desc {
 
 enum sdhci_cookie {
        COOKIE_UNMAPPED,
-       COOKIE_MAPPED,
-       COOKIE_GIVEN,
+       COOKIE_PRE_MAPPED,      /* mapped by sdhci_pre_req() */
+       COOKIE_MAPPED,          /* mapped by sdhci_prepare_data() */
 };
 
 struct sdhci_host {