Commit bab76961 authored by Pierre Ossman's avatar Pierre Ossman Committed by Russell King
Browse files

[MMC] sdhci: Avoid sdhci DMA boundaries 



The sdhci controllers will issue an interrupt when a configurable number of
bytes have been transfered using DMA. The purpose is to handle multiple,
scattered memory pages.

Unfortunately, it requires that all transfers are completely aligned to
memory pages, which we cannot guarantee. So we just disable the function.

Signed-off-by: default avatarPierre Ossman <drzeus@drzeus.cx>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent a406f5a3

drivers/mmc/sdhci.c

+9 −4
Original line number Diff line number Diff line
@@ -326,6 +326,9 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data) 
	DBG("tsac %d ms nsac %d clk\n",

		data->timeout_ns / 1000000, data->timeout_clks);



	/* Sanity checks */

	BUG_ON(data->blksz * data->blocks > 524288);



	/* timeout in us */

	target_timeout = data->timeout_ns / 1000 +

		data->timeout_clks / host->clock;
@@ -375,7 +378,9 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data) 
		host->remain = host->cur_sg->length;

	}



	writew(data->blksz, host->ioaddr + SDHCI_BLOCK_SIZE);

	/* We do not handle DMA boundaries, so set it to max (512 KiB) */

	writew(SDHCI_MAKE_BLKSZ(7, data->blksz),

		host->ioaddr + SDHCI_BLOCK_SIZE);

	writew(data->blocks, host->ioaddr + SDHCI_BLOCK_COUNT);

}
@@ -1188,10 +1193,10 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot) 
	mmc->max_phys_segs = 16;



	/*

	 * Maximum number of sectors in one transfer. Limited by sector

	 * count register.

	 * Maximum number of sectors in one transfer. Limited by DMA boundary

	 * size (512KiB), which means (512 KiB/512=) 1024 entries.

	 */

	mmc->max_sectors = 0x3FFF;

	mmc->max_sectors = 1024;



	/*

	 * Maximum segment size. Could be one segment with the maximum number

drivers/mmc/sdhci.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#define SDHCI_DMA_ADDRESS	0x00



#define SDHCI_BLOCK_SIZE	0x04

#define  SDHCI_MAKE_BLKSZ(dma, blksz) (((dma & 0x7) << 12) | (blksz & 0xFFF))



#define SDHCI_BLOCK_COUNT	0x06

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