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Commit de0b65a7 authored by Russell King's avatar Russell King Committed by Chris Ball
Browse files

mmc: sdhci: avoid sync'ing the SG if there's no misalignment 



On read, we don't need to sync the whole scatterlist and then check
whether any segments need copying - if we check first, we avoid
potentially expensive cache handling.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Tested-by: default avatarMarkus Pargmann <mpa@pengutronix.de>
Tested-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Signed-off-by: default avatarChris Ball <chris@printf.net>
parent 0718e59a

drivers/mmc/host/sdhci.c

+10 −1
Original line number Diff line number Diff line
@@ -602,6 +602,7 @@ static void sdhci_adma_table_post(struct sdhci_host *host, 
	u8 *align;

	char *buffer;

	unsigned long flags;

	bool has_unaligned;



	if (data->flags & MMC_DATA_READ)

		direction = DMA_FROM_DEVICE;
@@ -614,7 +615,15 @@ static void sdhci_adma_table_post(struct sdhci_host *host, 
	dma_unmap_single(mmc_dev(host->mmc), host->align_addr,

		128 * 4, direction);



	if (data->flags & MMC_DATA_READ) {

	/* Do a quick scan of the SG list for any unaligned mappings */

	has_unaligned = false;

	for_each_sg(data->sg, sg, host->sg_count, i)

		if (sg_dma_address(sg) & 3) {

			has_unaligned = true;

			break;

		}



	if (has_unaligned && data->flags & MMC_DATA_READ) {

		dma_sync_sg_for_cpu(mmc_dev(host->mmc), data->sg,

			data->sg_len, direction);