[PATCH] libata DMADIR support

[Jeff Garzik <jgarzik@pobox.com>]

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This patch goes by the specification -- which means it apparently 
doesn't work with at least one bridge.  So modify this patch as necessary.

Until a definitive solution is found, DMADIR will remain a "branch" off 
the main work.



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diff -Nru a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
--- a/drivers/scsi/libata-core.c	Sat May 15 17:44:43 2004
+++ b/drivers/scsi/libata-core.c	Sat May 15 17:44:43 2004
@@ -1167,6 +1167,9 @@
 		if (ata_id_is_ata(dev))		/* sanity check */
 			goto err_out_nosup;
 
+		if (ata_id_use_dmadir(dev))
+			dev->flags |= ATA_DFLAG_DMADIR;
+
 		/* see if 16-byte commands supported */
 		tmp = dev->id[0] & 0x3;
 		if (tmp == 1)
diff -Nru a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
--- a/drivers/scsi/libata-scsi.c	Sat May 15 17:44:43 2004
+++ b/drivers/scsi/libata-scsi.c	Sat May 15 17:44:43 2004
@@ -920,6 +920,9 @@
 		qc->flags |= ATA_QCFLAG_SG; /* data is present; dma-map it */
 		qc->tf.protocol = ATA_PROT_ATAPI_DMA;
 		qc->tf.feature |= ATAPI_PKT_DMA;
+		if ((qc->dev->flags & ATA_DFLAG_DMADIR) &&
+		    (cmd->sc_data_direction != SCSI_DATA_WRITE))
+			qc->tf.feature |= ATAPI_DMADIR;
 	}
 
 	return 0;
diff -Nru a/include/linux/ata.h b/include/linux/ata.h
--- a/include/linux/ata.h	Sat May 15 17:44:43 2004
+++ b/include/linux/ata.h	Sat May 15 17:44:43 2004
@@ -134,6 +134,8 @@
 
 	/* ATAPI stuff */
 	ATAPI_PKT_DMA		= (1 << 0),
+	ATAPI_DMADIR		= (1 << 2),	/* ATAPI data dir:
+						   0=to device, 1=to host */
 
 	/* cable types */
 	ATA_CBL_NONE		= 0,
@@ -203,6 +205,7 @@
 #define ata_id_has_wcache(dev)	((dev)->id[82] & (1 << 5))
 #define ata_id_has_lba(dev)	((dev)->id[49] & (1 << 8))
 #define ata_id_has_dma(dev)	((dev)->id[49] & (1 << 9))
+#define ata_id_use_dmadir(dev)	((dev)->id[62] & (1 << 15))
 #define ata_id_u32(dev,n)	\
 	(((u32) (dev)->id[(n) + 1] << 16) | ((u32) (dev)->id[(n)]))
 #define ata_id_u64(dev,n)	\
diff -Nru a/include/linux/libata.h b/include/linux/libata.h
--- a/include/linux/libata.h	Sat May 15 17:44:43 2004
+++ b/include/linux/libata.h	Sat May 15 17:44:43 2004
@@ -90,6 +90,7 @@
 	ATA_DFLAG_MASTER	= (1 << 2), /* is device 0? */
 	ATA_DFLAG_WCACHE	= (1 << 3), /* has write cache we can
 					     * (hopefully) flush? */
+	ATA_DFLAG_DMADIR	= (1 << 4), /* use DMADIR bit in ATAPI */
 
 	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
 	ATA_DEV_ATA		= 1,	/* ATA device */