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Commit 6a87e42e authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
Browse files

libata: implement ATA_HORKAGE_ATAPI_MOD16_DMA and apply it 

libata always uses PIO for ATAPI commands when the number of bytes to
transfer isn't multiple of 16 but quantum DAT72 chokes on odd bytes
PIO transfers.  Implement a horkage to skip the mod16 check and apply
it to the quantum device.

This is reported by John Clark in the following thread.

  http://thread.gmane.org/gmane.linux.ide/34748



Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: John Clark <clarkjc@runbox.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
parent a464189d

drivers/ata/libata-core.c

+3 −1
Original line number Diff line number Diff line
@@ -4024,6 +4024,7 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = { 


	/* Weird ATAPI devices */

	{ "TORiSAN DVD-ROM DRD-N216", NULL,	ATA_HORKAGE_MAX_SEC_128 },

	{ "QUANTUM DAT    DAT72-000", NULL,	ATA_HORKAGE_ATAPI_MOD16_DMA },



	/* Devices we expect to fail diagnostics */
@@ -4444,7 +4445,8 @@ int atapi_check_dma(struct ata_queued_cmd *qc) 
	/* Don't allow DMA if it isn't multiple of 16 bytes.  Quite a

	 * few ATAPI devices choke on such DMA requests.

	 */

	if (unlikely(qc->nbytes & 15))

	if (!(qc->dev->horkage & ATA_HORKAGE_ATAPI_MOD16_DMA) &&

	    unlikely(qc->nbytes & 15))

		return 1;



	if (ap->ops->check_atapi_dma)

include/linux/libata.h

+2 −0
Original line number Diff line number Diff line
@@ -373,6 +373,8 @@ enum { 
	ATA_HORKAGE_IVB		= (1 << 8),	/* cbl det validity bit bugs */

	ATA_HORKAGE_STUCK_ERR	= (1 << 9),	/* stuck ERR on next PACKET */

	ATA_HORKAGE_BRIDGE_OK	= (1 << 10),	/* no bridge limits */

	ATA_HORKAGE_ATAPI_MOD16_DMA = (1 << 11), /* use ATAPI DMA for commands

						    not multiple of 16 bytes */



	 /* DMA mask for user DMA control: User visible values; DO NOT

	    renumber */