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>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 2e6e162..57a4364 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2343,8 +2343,8 @@
{
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 @@
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 @@
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;
