diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 10aa278..4f115ad 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -658,6 +658,10 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
 	unsigned int offset;
 	unsigned char *buf;
 
+	if (!qc->cursg) {
+		qc->curbytes = qc->nbytes;
+		return;
+	}
 	if (qc->curbytes == qc->nbytes - qc->sect_size)
 		ap->hsm_task_state = HSM_ST_LAST;
 
@@ -683,6 +687,8 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
 
 	if (qc->cursg_ofs == qc->cursg->length) {
 		qc->cursg = sg_next(qc->cursg);
+		if (!qc->cursg)
+			ap->hsm_task_state = HSM_ST_LAST;
 		qc->cursg_ofs = 0;
 	}
 }