RDMA/bnxt_re: Disable doorbell moderation if hardware register read fails

If the HW register read fails, the FIFO will be always shown as
full. DB moderation doesn't work in that case and the traffic fails.
So disable this feature and log a message.

Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Link: https://lore.kernel.org/r/1719456065-27394-4-git-send-email-selvin.xavier@broadcom.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

1 files changed, 34 insertions, 11 deletions

diff --git a/drivers/infiniband/hw/bnxt_re/main.c b/drivers/infiniband/hw/bnxt_re/main.c
index 2c5282fdc9f7..9714b9ab7524 100644
--- a/drivers/infiniband/hw/bnxt_re/main.c
+++ b/drivers/infiniband/hw/bnxt_re/main.c
@@ -488,19 +488,40 @@ static void bnxt_re_set_default_pacing_data(struct bnxt_re_dev *rdev)
 		pacing_data->pacing_th * BNXT_RE_PACING_ALARM_TH_MULTIPLE;
 }
 
-static void __wait_for_fifo_occupancy_below_th(struct bnxt_re_dev *rdev)
+static u32 __get_fifo_occupancy(struct bnxt_re_dev *rdev)
 {
 	struct bnxt_qplib_db_pacing_data *pacing_data = rdev->qplib_res.pacing_data;
 	u32 read_val, fifo_occup;
 
+	read_val = readl(rdev->en_dev->bar0 + rdev->pacing.dbr_db_fifo_reg_off);
+	fifo_occup = pacing_data->fifo_max_depth -
+		     ((read_val & pacing_data->fifo_room_mask) >>
+		      pacing_data->fifo_room_shift);
+	return fifo_occup;
+}
+
+static bool is_dbr_fifo_full(struct bnxt_re_dev *rdev)
+{
+	u32 max_occup, fifo_occup;
+
+	fifo_occup = __get_fifo_occupancy(rdev);
+	max_occup = BNXT_RE_MAX_FIFO_DEPTH(rdev->chip_ctx) - 1;
+	if (fifo_occup == max_occup)
+		return true;
+
+	return false;
+}
+
+static void __wait_for_fifo_occupancy_below_th(struct bnxt_re_dev *rdev)
+{
+	struct bnxt_qplib_db_pacing_data *pacing_data = rdev->qplib_res.pacing_data;
+	u32 fifo_occup;
+
 	/* loop shouldn't run infintely as the occupancy usually goes
 	 * below pacing algo threshold as soon as pacing kicks in.
 	 */
 	while (1) {
-		read_val = readl(rdev->en_dev->bar0 + rdev->pacing.dbr_db_fifo_reg_off);
-		fifo_occup = pacing_data->fifo_max_depth -
-			     ((read_val & pacing_data->fifo_room_mask) >>
-			      pacing_data->fifo_room_shift);
+		fifo_occup = __get_fifo_occupancy(rdev);
 		/* Fifo occupancy cannot be greater the MAX FIFO depth */
 		if (fifo_occup > pacing_data->fifo_max_depth)
 			break;
@@ -556,16 +577,13 @@ static void bnxt_re_pacing_timer_exp(struct work_struct *work)
 	struct bnxt_re_dev *rdev = container_of(work, struct bnxt_re_dev,
 			dbq_pacing_work.work);
 	struct bnxt_qplib_db_pacing_data *pacing_data;
-	u32 read_val, fifo_occup;
+	u32 fifo_occup;
 
 	if (!mutex_trylock(&rdev->pacing.dbq_lock))
 		return;
 
 	pacing_data = rdev->qplib_res.pacing_data;
-	read_val = readl(rdev->en_dev->bar0 + rdev->pacing.dbr_db_fifo_reg_off);
-	fifo_occup = pacing_data->fifo_max_depth -
-		     ((read_val & pacing_data->fifo_room_mask) >>
-		      pacing_data->fifo_room_shift);
+	fifo_occup = __get_fifo_occupancy(rdev);
 
 	if (fifo_occup > pacing_data->pacing_th)
 		goto restart_timer;
@@ -613,7 +631,6 @@ void bnxt_re_pacing_alert(struct bnxt_re_dev *rdev)
 
 static int bnxt_re_initialize_dbr_pacing(struct bnxt_re_dev *rdev)
 {
-
 	/* Allocate a page for app use */
 	rdev->pacing.dbr_page = (void *)__get_free_page(GFP_KERNEL);
 	if (!rdev->pacing.dbr_page)
@@ -637,6 +654,12 @@ static int bnxt_re_initialize_dbr_pacing(struct bnxt_re_dev *rdev)
 	rdev->pacing.dbr_bar_addr =
 		pci_resource_start(rdev->qplib_res.pdev, 0) + rdev->pacing.dbr_db_fifo_reg_off;
 
+	if (is_dbr_fifo_full(rdev)) {
+		free_page((u64)rdev->pacing.dbr_page);
+		rdev->pacing.dbr_page = NULL;
+		return -EIO;
+	}
+
 	rdev->pacing.pacing_algo_th = BNXT_RE_PACING_ALGO_THRESHOLD;
 	rdev->pacing.dbq_pacing_time = BNXT_RE_DBR_PACING_TIME;
 	rdev->pacing.dbr_def_do_pacing = BNXT_RE_DBR_DO_PACING_NO_CONGESTION;