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Commit 299b3f8d authored by Mark Lord's avatar Mark Lord Committed by Jeff Garzik
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sata_mv: workaround for multi_count errata sata24 



Workaround for errata SATA#24 in sata_mv.
This errata affects WRITE_MULTI* commands when
the device multi_count produces a DRQ block size >= 4Kbytes.

We work around it here by converting such operations
into ordinary PIO_WRITEs instead.

Note that this might result in a PIO FUA write unavoidably being converted
into a non-FUA write.  In practice, any system using FUA is also going to be
using DMA rather than PIO, so this shouldn't affect anyone in the real world.

Signed-off-by: default avatarMark Lord <mlord@pobox.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent 8d2b450d

drivers/ata/sata_mv.c

+42 −2
Original line number Diff line number Diff line
@@ -1881,6 +1881,39 @@ static u8 mv_bmdma_status(struct ata_port *ap) 
	return status;

}



static void mv_rw_multi_errata_sata24(struct ata_queued_cmd *qc)

{

	struct ata_taskfile *tf = &qc->tf;

	/*

	 * Workaround for 88SX60x1 FEr SATA#24.

	 *

	 * Chip may corrupt WRITEs if multi_count >= 4kB.

	 * Note that READs are unaffected.

	 *

	 * It's not clear if this errata really means "4K bytes",

	 * or if it always happens for multi_count > 7

	 * regardless of device sector_size.

	 *

	 * So, for safety, any write with multi_count > 7

	 * gets converted here into a regular PIO write instead:

	 */

	if ((tf->flags & ATA_TFLAG_WRITE) && is_multi_taskfile(tf)) {

		if (qc->dev->multi_count > 7) {

			switch (tf->command) {

			case ATA_CMD_WRITE_MULTI:

				tf->command = ATA_CMD_PIO_WRITE;

				break;

			case ATA_CMD_WRITE_MULTI_FUA_EXT:

				tf->flags &= ~ATA_TFLAG_FUA; /* ugh */

				/* fall through */

			case ATA_CMD_WRITE_MULTI_EXT:

				tf->command = ATA_CMD_PIO_WRITE_EXT;

				break;

			}

		}

	}

}



/**

 *      mv_qc_prep - Host specific command preparation.

 *      @qc: queued command to prepare
@@ -1902,9 +1935,16 @@ static void mv_qc_prep(struct ata_queued_cmd *qc) 
	u16 flags = 0;

	unsigned in_index;



	if ((tf->protocol != ATA_PROT_DMA) &&

	    (tf->protocol != ATA_PROT_NCQ))

	switch (tf->protocol) {

	case ATA_PROT_DMA:

	case ATA_PROT_NCQ:

		break;	/* continue below */

	case ATA_PROT_PIO:

		mv_rw_multi_errata_sata24(qc);

		return;

	default:

		return;

	}



	/* Fill in command request block

	 */