[PATCH] libata: implement qc->result_tf

Add qc->result_tf and ATA_QCFLAG_RESULT_TF.  This moves the
responsibility of loading result TF from post-compltion path to qc
execution path.  qc->result_tf is loaded if explicitly requested or
the qc failsa.  This allows more efficient completion implementation
and correct handling of result TF for controllers which don't have
global TF representation such as sil3124/32.

Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index 0e1a3be39475..a4b8a419caad 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -162,7 +162,9 @@ enum {
         ATA_QCFLAG_SINGLE       = (1 << 2), /* no s/g, just a single buffer */
         ATA_QCFLAG_DMAMAP       = ATA_QCFLAG_SG | ATA_QCFLAG_SINGLE,
         ATA_QCFLAG_IO           = (1 << 3), /* standard IO command */
-        ATA_QCFLAG_EH_SCHEDULED = (1 << 4), /* EH scheduled */
+        ATA_QCFLAG_RESULT_TF    = (1 << 4), /* result TF requested */
+
+        ATA_QCFLAG_EH_SCHEDULED = (1 << 16), /* EH scheduled */
 
         /* host set flags */
         ATA_HOST_SIMPLEX        = (1 << 0),     /* Host is simplex, one DMA channel per host_set only */
@@ -343,7 +345,7 @@ struct ata_queued_cmd {
         struct scatterlist      *__sg;
 
         unsigned int            err_mask;
-
+        struct ata_taskfile     result_tf;
         ata_qc_cb_t             complete_fn;
 
         void                    *private_data;
@@ -824,6 +826,10 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc)
         qc->err_mask = 0;
 
         ata_tf_init(qc->ap, &qc->tf, qc->dev->devno);
+
+        /* init result_tf such that it indicates normal completion */
+        qc->result_tf.command = ATA_DRDY;
+        qc->result_tf.feature = 0;
 }
 
 /**
@@ -839,9 +845,15 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc)
  */
 static inline void ata_qc_complete(struct ata_queued_cmd *qc)
 {
+        struct ata_port *ap = qc->ap;
+
         if (unlikely(qc->flags & ATA_QCFLAG_EH_SCHEDULED))
                 return;
 
+        /* read result TF if failed or requested */
+        if (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF)
+                ap->ops->tf_read(ap, &qc->result_tf);
+
         __ata_qc_complete(qc);
 }