If hba_maxq equals poll_queues, which means there are no I/O queues
(HCTX_TYPE_DEFAULT, HCTX_TYPE_READ), the very first hw queue will be
allocated as HCTX_TYPE_POLL and it will be used as the dev_cmd_queue.
In this case, device commands such as QUERY cannot be properly handled.

This patch prevents the initialization of MCQ when the number of I/O
queues is not set and only the number of POLL queues is set.

Signed-off-by: Minwoo Im <minwoo.im@samsung.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufs-mcq.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
index 46faa54aea94..4bcae410c268 100644
--- a/drivers/ufs/core/ufs-mcq.c
+++ b/drivers/ufs/core/ufs-mcq.c
@@ -179,6 +179,15 @@ static int ufshcd_mcq_config_nr_queues(struct ufs_hba *hba)
 		return -EOPNOTSUPP;
 	}
 
+	/*
+	 * Device should support at least one I/O queue to handle device
+	 * commands via hba->dev_cmd_queue.
+	 */
+	if (hba_maxq == poll_queues) {
+		dev_err(hba->dev, "At least one non-poll queue required\n");
+		return -EOPNOTSUPP;
+	}
+
 	rem = hba_maxq;
 
 	if (rw_queues) {
-- 
2.34.1