Commit 94538e51 authored Jan 26, 2016 by Russell King Committed by Ulf Hansson Feb 29, 2016

mmc: sdhci: clean up host cookie handling



Commit d31911b9 ("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>

parent f48f039c

drivers/mmc/host/sdhci.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -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)

drivers/mmc/host/sdhci.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -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 {