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authorTejun Heo <tj@kernel.org>2008-06-17 12:36:26 +0900
committerJeff Garzik <jgarzik@redhat.com>2008-06-18 20:27:49 -0400
commit5895ef9a5b746e7cc9ebda50c87fbd11562da0a4 (patch)
tree264ed72edfef60f11260f3227523334b1e1aca80 /drivers/ata/libata-scsi.c
parentd799e083a80b220f3681d7790f11e77d1704022b (diff)
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libata: don't check whether to use DMA or not for no data commands
There's no reason to check whether to use DMA or not for no data commands. Don't do it. While at it, make local variable using_pio in atapi_xlat() set iff ATAPI_PROT_PIO is going to be used and rename ata_check_atapi_dma() to atapi_check_dma() for consistency. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Diffstat (limited to 'drivers/ata/libata-scsi.c')
-rw-r--r--drivers/ata/libata-scsi.c16
1 files changed, 7 insertions, 9 deletions
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 2e6e1622dc6d..57a43649a461 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2343,8 +2343,8 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
{
struct scsi_cmnd *scmd = qc->scsicmd;
struct ata_device *dev = qc->dev;
- int using_pio = (dev->flags & ATA_DFLAG_PIO);
int nodata = (scmd->sc_data_direction == DMA_NONE);
+ int using_pio = !nodata && (dev->flags & ATA_DFLAG_PIO);
unsigned int nbytes;
memset(qc->cdb, 0, dev->cdb_len);
@@ -2362,7 +2362,7 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
ata_qc_set_pc_nbytes(qc);
/* check whether ATAPI DMA is safe */
- if (!using_pio && ata_check_atapi_dma(qc))
+ if (!nodata && !using_pio && atapi_check_dma(qc))
using_pio = 1;
/* Some controller variants snoop this value for Packet
@@ -2402,13 +2402,11 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
qc->tf.lbam = (nbytes & 0xFF);
qc->tf.lbah = (nbytes >> 8);
- if (using_pio || nodata) {
- /* no data, or PIO data xfer */
- if (nodata)
- qc->tf.protocol = ATAPI_PROT_NODATA;
- else
- qc->tf.protocol = ATAPI_PROT_PIO;
- } else {
+ if (nodata)
+ qc->tf.protocol = ATAPI_PROT_NODATA;
+ else if (using_pio)
+ qc->tf.protocol = ATAPI_PROT_PIO;
+ else {
/* DMA data xfer */
qc->tf.protocol = ATAPI_PROT_DMA;
qc->tf.feature |= ATAPI_PKT_DMA;