RE: [PATCH linux-can] can: flexcan: enable RX FIFO after FRZ/HALT valid

-----Original Message-----
From: Marc Kleine-Budde <mkl@pengutronix.de>
Sent: 2021年2月2日 15:37
To: Joakim Zhang <redacted>; linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org; dl-linux-imx <redacted>
Subject: Re: [PATCH linux-can] can: flexcan: enable RX FIFO after FRZ/HALT
valid

On 2/2/21 7:23 AM, Joakim Zhang wrote:

quoted

RX FIFO enable failed could happen when do system reboot stress test,
one customer reports failure rate is about 50%.

[    0.303958] flexcan 5a8d0000.can: 5a8d0000.can supply xceiver not

found, using dummy regulator

quoted

[    0.304281] flexcan 5a8d0000.can (unnamed net_device) (uninitialized):

Could not enable RX FIFO, unsupported core

quoted

[    0.314640] flexcan 5a8d0000.can: registering netdev failed
[    0.320728] flexcan 5a8e0000.can: 5a8e0000.can supply xceiver not

found, using dummy regulator

quoted

[    0.320991] flexcan 5a8e0000.can (unnamed net_device) (uninitialized):

Could not enable RX FIFO, unsupported core

quoted

[    0.331360] flexcan 5a8e0000.can: registering netdev failed
[    0.337444] flexcan 5a8f0000.can: 5a8f0000.can supply xceiver not found,

using dummy regulator

quoted

[    0.337716] flexcan 5a8f0000.can (unnamed net_device) (uninitialized):

Could not enable RX FIFO, unsupported core

quoted

[    0.348117] flexcan 5a8f0000.can: registering netdev failed

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

Fixes: e955cead03117 ("CAN: Add Flexcan CAN controller driver")
Signed-off-by: Joakim Zhang <redacted>
---
 drivers/net/can/flexcan.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 038fe1036df2..8ee9fa2f4161 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c

@@ -1803,6 +1803,7 @@ static int register_flexcandev(struct net_device

*dev)  {
 	struct flexcan_priv *priv = netdev_priv(dev);
 	struct flexcan_regs __iomem *regs = priv->regs;
+	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
 	u32 reg, err;

 	err = flexcan_clks_enable(priv);

@@ -1825,10 +1826,19 @@ static int register_flexcandev(struct net_device

*dev)

quoted

 	if (err)
 		goto out_chip_disable;

-	/* set freeze, halt and activate FIFO, restrict register access */
+	/* set freeze, halt and polling the freeze ack */
 	reg = priv->read(&regs->mcr);
-	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT |
-		FLEXCAN_MCR_FEN | FLEXCAN_MCR_SUPV;
+	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT;
+	priv->write(reg, &regs->mcr);
+
+	while (timeout-- && !(priv->read(&regs->mcr) &

FLEXCAN_MCR_FRZ_ACK))

quoted

+		udelay(100);

Please make use of existing functions like flexcan_chip_freeze().

OK, will improve it. Marc, I notice this issue also exist in flexcan_chip_start(), should I fix it together? 

Best Regards,
Joakim Zhang

regards,
Marc

--
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