On Friday, April 22, 2016 11:32:00 AM David Laight wrote:
> From: Andy Shevchenko
> > Sent: 21 April 2016 19:15
> > ata_sff_qc_issue() can't handle DMA commands and thus we have to avoid it 
> > for
> > them. Do call ata_bmdma_qc_issue() instead for this case.
> > 
> > Suggested-by: Christian Lamparter <chunk...@googlemail.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
> > ---
> >  drivers/ata/sata_dwc_460ex.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
> > index 038e5fb..845c35d 100644
> > --- a/drivers/ata/sata_dwc_460ex.c
> > +++ b/drivers/ata/sata_dwc_460ex.c
> > @@ -1061,10 +1061,12 @@ static unsigned int sata_dwc_qc_issue(struct 
> > ata_queued_cmd *qc)
> >                     __func__, tag, qc->ap->link.sactive, sactive);
> > 
> >             ap->ops->sff_tf_load(ap, &qc->tf);
> > -           sata_dwc_exec_command_by_tag(ap, &qc->tf, qc->tag,
> > +           sata_dwc_exec_command_by_tag(ap, &qc->tf, tag,
> >                                          SATA_DWC_CMD_ISSUED_PEND);
> > +   } else if (ata_is_dma(qc->tf.protocol)) {
> > +           return ata_bmdma_qc_issue(qc);
> >     } else {
> > -           ata_sff_qc_issue(qc);
> > +           return ata_sff_qc_issue(qc);
> >     }
> >     return 0;
> >  }
> 
> I'd nuke those 'else if', they make it very hard to read.
> I Think the code is:
> 
>               sata_dwc_exec_command_by_tag(...);
>               return 0;
>       }
> 
>       if (ata_is_dma(qc->tf.protocol))
>               return ata_bmdma_qc_issue(qc);
> 
>       return ata_sff_qc_issue(qc);
> }

What about something like this instead? ata_bmdma_qc_issue already calls
ata_sff_qc_issue, if it's not a dma transfere anyway [0].
---
diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
index 6a61184..67cce54 100644
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -1096,12 +1096,9 @@ static unsigned int sata_dwc_qc_issue(struct 
ata_queued_cmd *qc)
                ap->ops->sff_tf_load(ap, &qc->tf);
                sata_dwc_exec_command_by_tag(ap, &qc->tf, tag,
                                             SATA_DWC_CMD_ISSUED_PEND);
-       } else if (ata_is_dma(qc->tf.protocol)) {
+               return 0;
+       } else
                return ata_bmdma_qc_issue(qc);
-       } else {
-               return ata_sff_qc_issue(qc);
-       }
-       return 0;
 }
 
 static void sata_dwc_error_handler(struct ata_port *ap)
---

[0] <http://lxr.free-electrons.com/source/drivers/ata/libata-sff.c#L2787>
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