1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 75fde48e1a73..28092bc50146 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1595,6 +1595,24 @@ static unsigned int mv_qc_issue(struct ata_queued_cmd *qc)
 
         if ((qc->tf.protocol != ATA_PROT_DMA) &&
             (qc->tf.protocol != ATA_PROT_NCQ)) {
+                static int limit_warnings = 10;
+                /*
+                 * Errata SATA#16, SATA#24: warn if multiple DRQs expected.
+                 *
+                 * Someday, we might implement special polling workarounds
+                 * for these, but it all seems rather unnecessary since we
+                 * normally use only DMA for commands which transfer more
+                 * than a single block of data.
+                 *
+                 * Much of the time, this could just work regardless.
+                 * So for now, just log the incident, and allow the attempt.
+                 */
+                if (limit_warnings && (qc->nbytes / qc->sect_size) > 1) {
+                        --limit_warnings;
+                        ata_link_printk(qc->dev->link, KERN_WARNING, DRV_NAME
+                                        ": attempting PIO w/multiple DRQ: "
+                                        "this may fail due to h/w errata\n");
+                }
                 /*
                  * We're about to send a non-EDMA capable command to the
                  * port.  Turn off EDMA so there won't be problems accessing