Subject: [PATCH V2 net 07/11] net: ena: allow automatic fallback to polling mode

From: <[email-masked]>
Date: Mon, 3 Jun 2019 17:43:25 +0300

From: Sameeh Jubran <[email-masked]>

Enable fallback to polling mode for Admin queue
when identified a command response arrival
without an accompanying MSI-X interrupt

Signed-off-by: Igor Chauskin <[email-masked]>
Signed-off-by: Sameeh Jubran <[email-masked]>
---
 drivers/net/ethernet/amazon/ena/ena_com.c | 34 +++++++++++++++++------
 drivers/net/ethernet/amazon/ena/ena_com.h | 14 ++++++++++
 2 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 139b31549..5e2abdda7 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -762,16 +762,26 @@ static int ena_com_wait_and_process_admin_cq_interrupts(struct ena_comp_ctx *com
 		admin_queue->stats.no_completion++;
 		spin_unlock_irqrestore(&admin_queue->q_lock, flags);
 
-		if (comp_ctx->status == ENA_CMD_COMPLETED)
-			pr_err("The ena device have completion but the driver didn't receive any MSI-X interrupt (cmd %d)\n",
-			       comp_ctx->cmd_opcode);
-		else
-			pr_err("The ena device doesn't send any completion for the admin cmd %d status %d\n",
+		if (comp_ctx->status == ENA_CMD_COMPLETED) {
+			pr_err("The ena device sent a completion but the driver didn't receive a MSI-X interrupt (cmd %d), autopolling mode is %s\n",
+			       comp_ctx->cmd_opcode,
+			       admin_queue->auto_polling ? "ON" : "OFF");
+			/* Check if fallback to polling is enabled */
+			if (admin_queue->auto_polling)
+				admin_queue->polling = true;
+		} else {
+			pr_err("The ena device doesn't send a completion for the admin cmd %d status %d\n",
 			       comp_ctx->cmd_opcode, comp_ctx->status);
-
-		admin_queue->running_state = false;
-		ret = -ETIME;
-		goto err;
+		}
+		/* Check if shifted to polling mode.
+		 * This will happen if there is a completion without an interrupt
+		 * and autopolling mode is enabled. Continuing normal execution in such case
+		 */
+		if (!admin_queue->polling) {
+			admin_queue->running_state = false;
+			ret = -ETIME;
+			goto err;
+		}
 	}
 
 	ret = ena_com_comp_status_to_errno(comp_ctx->comp_status);
@@ -1650,6 +1660,12 @@ void ena_com_set_admin_polling_mode(struct ena_com_dev *ena_dev, bool polling)
 	ena_dev->admin_queue.polling = polling;
 }
 
+void ena_com_set_admin_auto_polling_mode(struct ena_com_dev *ena_dev,
+					 bool polling)
+{
+	ena_dev->admin_queue.auto_polling = polling;
+}
+
 int ena_com_mmio_reg_read_request_init(struct ena_com_dev *ena_dev)
 {
 	struct ena_com_mmio_read *mmio_read = &ena_dev->mmio_read;
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h
index ce36444c3..6d356cb05 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_com.h
@@ -283,6 +283,9 @@ struct ena_com_admin_queue {
 	/* Indicate if the admin queue should poll for completion */
 	bool polling;
 
+	/* Define if fallback to polling mode should occur */
+	bool auto_polling;
+
 	u16 curr_cmd_id;
 
 	/* Indicate that the ena was initialized and can
@@ -545,6 +548,17 @@ void ena_com_set_admin_polling_mode(struct ena_com_dev *ena_dev, bool polling);
  */
 bool ena_com_get_ena_admin_polling_mode(struct ena_com_dev *ena_dev);
 
+/* ena_com_set_admin_auto_polling_mode - Enable autoswitch to polling mode
+ * @ena_dev: ENA communication layer struct
+ * @polling: Enable/Disable polling mode
+ *
+ * Set the autopolling mode.
+ * If autopolling is on:
+ * In case of missing interrupt when data is available switch to polling.
+ */
+void ena_com_set_admin_auto_polling_mode(struct ena_com_dev *ena_dev,
+					 bool polling);
+
 /* ena_com_admin_q_comp_intr_handler - admin queue interrupt handler
  * @ena_dev: ENA communication layer struct
  *
-- 
2.17.1