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@xxxxxxxxxx>
---
It's late in the -rc cycle but these two patches are to work around
specific hardware and low risk. Thanks.
drivers/ata/libata-core.c | 4 ++--
drivers/ata/libata-scsi.c | 16 +++++++---------
drivers/ata/libata.h | 2 +-
3 files changed, 10 insertions(+), 12 deletions(-)
Index: work/drivers/ata/libata-scsi.c
===================================================================
--- work.orig/drivers/ata/libata-scsi.c
+++ work/drivers/ata/libata-scsi.c
@@ -2343,8 +2343,8 @@ static unsigned int atapi_xlat(struct at
{
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 at
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 at
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;
Index: work/drivers/ata/libata-core.c
===================================================================
--- work.orig/drivers/ata/libata-core.c
+++ work/drivers/ata/libata-core.c
@@ -4297,7 +4297,7 @@ void ata_sg_clean(struct ata_queued_cmd
}
/**
- * ata_check_atapi_dma - Check whether ATAPI DMA can be supported
+ * atapi_check_dma - Check whether ATAPI DMA can be supported
* @qc: Metadata associated with taskfile to check
*
* Allow low-level driver to filter ATA PACKET commands, returning
@@ -4310,7 +4310,7 @@ void ata_sg_clean(struct ata_queued_cmd
* RETURNS: 0 when ATAPI DMA can be used
* nonzero otherwise
*/
-int ata_check_atapi_dma(struct ata_queued_cmd *qc)
+int atapi_check_dma(struct ata_queued_cmd *qc)
{
struct ata_port *ap = qc->ap;
Index: work/drivers/ata/libata.h
===================================================================
--- work.orig/drivers/ata/libata.h
+++ work/drivers/ata/libata.h
@@ -106,7 +106,7 @@ extern void ata_sg_clean(struct ata_queu
extern void ata_qc_free(struct ata_queued_cmd *qc);
extern void ata_qc_issue(struct ata_queued_cmd *qc);
extern void __ata_qc_complete(struct ata_queued_cmd *qc);
-extern int ata_check_atapi_dma(struct ata_queued_cmd *qc);
+extern int atapi_check_dma(struct ata_queued_cmd *qc);
extern void swap_buf_le16(u16 *buf, unsigned int buf_words);
extern void ata_dev_init(struct ata_device *dev);
extern void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp);
--
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