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mmc: sdhci: clean up host cookie handling 

Commit d31911b937 ("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>
This commit is contained in:
Russell King 2016-01-26 13:40:37 +00:00 committed by Ulf Hansson
parent f48f039cd2
commit 94538e51d6
2 changed files with 8 additions and 8 deletions
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12
drivers/mmc/host/sdhci.c
View File

@ -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)

4
drivers/mmc/host/sdhci.h
View File

@ -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 {