[PATCH 4.14 10/95] can: flexcan: enable RX FIFO after FRZ/HALT valid

[gregkh@xxxxxxxxxxxxxxxxxxx]

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

From: Joakim Zhang <qiangqing.zhang@xxxxxxx>

commit ec15e27cc8904605846a354bb1f808ea1432f853 upstream.

RX FIFO enable failed could happen when do system reboot stress test:

[    0.303958] flexcan 5a8d0000.can: 5a8d0000.can supply xceiver not found, using dummy regulator
[    0.304281] flexcan 5a8d0000.can (unnamed net_device) (uninitialized): Could not enable RX FIFO, unsupported core
[    0.314640] flexcan 5a8d0000.can: registering netdev failed
[    0.320728] flexcan 5a8e0000.can: 5a8e0000.can supply xceiver not found, using dummy regulator
[    0.320991] flexcan 5a8e0000.can (unnamed net_device) (uninitialized): Could not enable RX FIFO, unsupported core
[    0.331360] flexcan 5a8e0000.can: registering netdev failed
[    0.337444] flexcan 5a8f0000.can: 5a8f0000.can supply xceiver not found, using dummy regulator
[    0.337716] flexcan 5a8f0000.can (unnamed net_device) (uninitialized): Could not enable RX FIFO, unsupported core
[    0.348117] flexcan 5a8f0000.can: registering netdev failed

RX FIFO should be enabled after the FRZ/HALT are valid. But the current
code enable RX FIFO and FRZ/HALT at the same time.

Fixes: e955cead03117 ("CAN: Add Flexcan CAN controller driver")
Link: https://lore.kernel.org/r/20210218110037.16591-3-qiangqing.zhang@xxxxxxx
Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/can/flexcan.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1217,10 +1217,14 @@ static int register_flexcandev(struct ne
 	if (err)
 		goto out_chip_disable;
 
-	/* set freeze, halt and activate FIFO, restrict register access */
+	/* set freeze, halt */
+	err = flexcan_chip_freeze(priv);
+	if (err)
+		goto out_chip_disable;
+
+	/* activate FIFO, restrict register access */
 	reg = flexcan_read(&regs->mcr);
-	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT |
-		FLEXCAN_MCR_FEN | FLEXCAN_MCR_SUPV;
+	reg |=  FLEXCAN_MCR_FEN | FLEXCAN_MCR_SUPV;
 	flexcan_write(reg, &regs->mcr);
 
 	/* Currently we only support newer versions of this core