From de0b65a786ae83c8f6dfb712f65b9a36af70a981 Mon Sep 17 00:00:00 2001 From: Russell King Date: Fri, 25 Apr 2014 12:58:29 +0100 Subject: [PATCH] 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: Russell King Tested-by: Markus Pargmann Tested-by: Stephen Warren Signed-off-by: Ulf Hansson Signed-off-by: Chris Ball --- drivers/mmc/host/sdhci.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 074157e8e73d..4f878bcfaa2d 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -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); -- 2.34.1