1 files changed, 23 insertions, 9 deletions

diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index 44f9e5d9e362..ed5dc7cb50cd 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -791,11 +791,13 @@ static int nv_adma_check_atapi_dma(struct ata_queued_cmd *qc)
 
 static void nv_adma_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
 {
-        /* Since commands where a result TF is requested are not
-           executed in ADMA mode, the only time this function will be called
-           in ADMA mode will be if a command fails. In this case we
-           don't care about going into register mode with ADMA commands
-           pending, as the commands will all shortly be aborted anyway. */
+        /* Other than when internal or pass-through commands are executed,
+           the only time this function will be called in ADMA mode will be
+           if a command fails. In the failure case we don't care about going
+           into register mode with ADMA commands pending, as the commands will
+           all shortly be aborted anyway. We assume that NCQ commands are not
+           issued via passthrough, which is the only way that switching into
+           ADMA mode could abort outstanding commands. */
         nv_adma_register_mode(ap);
 
         ata_tf_read(ap, tf);
@@ -1359,11 +1361,9 @@ static int nv_adma_use_reg_mode(struct ata_queued_cmd *qc)
         struct nv_adma_port_priv *pp = qc->ap->private_data;
 
         /* ADMA engine can only be used for non-ATAPI DMA commands,
-           or interrupt-driven no-data commands, where a result taskfile
-           is not required. */
+           or interrupt-driven no-data commands. */
         if ((pp->flags & NV_ADMA_ATAPI_SETUP_COMPLETE) ||
-           (qc->tf.flags & ATA_TFLAG_POLLING) ||
-           (qc->flags & ATA_QCFLAG_RESULT_TF))
+           (qc->tf.flags & ATA_TFLAG_POLLING))
                 return 1;
 
         if ((qc->flags & ATA_QCFLAG_DMAMAP) ||
@@ -1381,6 +1381,8 @@ static void nv_adma_qc_prep(struct ata_queued_cmd *qc)
                        NV_CPB_CTL_IEN;
 
         if (nv_adma_use_reg_mode(qc)) {
+                BUG_ON(!(pp->flags & NV_ADMA_ATAPI_SETUP_COMPLETE) &&
+                        (qc->flags & ATA_QCFLAG_DMAMAP));
                 nv_adma_register_mode(qc->ap);
                 ata_qc_prep(qc);
                 return;
@@ -1425,9 +1427,21 @@ static unsigned int nv_adma_qc_issue(struct ata_queued_cmd *qc)
 
         VPRINTK("ENTER\n");
 
+        /* We can't handle result taskfile with NCQ commands, since
+           retrieving the taskfile switches us out of ADMA mode and would abort
+           existing commands. */
+        if (unlikely(qc->tf.protocol == ATA_PROT_NCQ &&
+                     (qc->flags & ATA_QCFLAG_RESULT_TF))) {
+                ata_dev_printk(qc->dev, KERN_ERR,
+                        "NCQ w/ RESULT_TF not allowed\n");
+                return AC_ERR_SYSTEM;
+        }
+
         if (nv_adma_use_reg_mode(qc)) {
                 /* use ATA register mode */
                 VPRINTK("using ATA register mode: 0x%lx\n", qc->flags);
+                BUG_ON(!(pp->flags & NV_ADMA_ATAPI_SETUP_COMPLETE) &&
+                        (qc->flags & ATA_QCFLAG_DMAMAP));
                 nv_adma_register_mode(qc->ap);
                 return ata_qc_issue_prot(qc);
         } else