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

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Date:   Tue, 2 Feb 2021 08:02:10 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH linux-can] can: flexcan: enable RX FIFO after FRZ/HALT
 valid


> -----Original Message-----
> From: Marc Kleine-Budde <mkl@...gutronix.de>
> Sent: 2021年2月2日 15:37
> To: Joakim Zhang <qiangqing.zhang@....com>; linux-can@...r.kernel.org
> Cc: netdev@...r.kernel.org; dl-linux-imx <linux-imx@....com>
> Subject: Re: [PATCH linux-can] can: flexcan: enable RX FIFO after FRZ/HALT
> valid
> 
> On 2/2/21 7:23 AM, Joakim Zhang wrote:
> > 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
> > [    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 set RX FIFO enable and FRZ/HALT at the same time.
> >
> > Fixes: e955cead03117 ("CAN: Add Flexcan CAN controller driver")
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> > ---
> >  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)
> >  	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))
> > +		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
> 
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
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