Re: [PATCH] can: xilinx: fix RX FIFO overflow error handling

[Andrea Scian - DAVE Embedded Systems]

Michal,
Kedar,

Any feedback regarding my patch?
Have you ever experienced such a problem?

Andrea SCIAN

*DAVE Embedded Systems*
via Talponedo 29/A 33080 Porcia (PN) - Italy
Telephone: +39.0434.921215
Telefax: +39.0434.1994030
web: www.dave.eu <http://www.dave.eu>


Il 24/07/2015 06:15, Michal Simek ha scritto:
> + Kedar
>
> On 07/23/2015 11:13 PM, Andrea Scian wrote:
> > Simply resetting the peripheral on RX FIFO overflow in not enough,
> > because we also need to re-initialize the whole device.
> > Also always enable RX FIFO overflow interrupt otherwise we may hang
> > until another interrupt arrives (this happens if FIFO overrun and just
> > read from CAN bus with candump)
> >
> > Signed-off-by: Andrea Scian <andrea.scian@xxxxxxx>
> > ---
> >
> > You can reproduce the problem with the following test-bed
> > * connect a Zynq based board to a PC with a CAN bus adapter (e.g. PCAN USB)
> > * start sending lots of CAN messages to Zynq system
> > * configure and start xilinx CAN driver
> > ** canconfig can0 bitrate 1000000
> > ** canconfig can0 start
> > * try to send/receive messages (cansend/candump)
> > * if you send a CAN message you'll get the RX FIFO error and additional messages
> > will not be received
> > * if you try to get messages you simple don't receive them (no interrupt triggered)
> > * with canconfig stop/start the hang goes away (if the others peers stop sending
> > send lots of messages ;-) )
> >
> > I tested the patch over xilinx-2014.04 kernel, but the patch applies cleanly to
> > mainline too.
> >
> > If someone has a better understanding of Xilinx CAN driver, please let me know if
> > it's better to handle the error in a different manner.
> >
> > Maybe the bus off handler need the same threadment too.
> >
> > TIA,
> >
> > Andrea Scian
> >
> > ---
> >   drivers/net/can/xilinx_can.c |    5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
> > index 5e8b560..c278177 100644
> > --- a/drivers/net/can/xilinx_can.c
> > +++ b/drivers/net/can/xilinx_can.c
> > @@ -100,6 +100,7 @@ enum xcan_reg {
> >   #define XCAN_INTR_ALL		(XCAN_IXR_TXOK_MASK | XCAN_IXR_BSOFF_MASK |\
> >   				 XCAN_IXR_WKUP_MASK | XCAN_IXR_SLP_MASK | \
> >   				 XCAN_IXR_RXNEMP_MASK | XCAN_IXR_ERROR_MASK | \
> > +				 XCAN_IXR_RXOFLW_MASK | \
> >   				 XCAN_IXR_ARBLST_MASK | XCAN_IXR_RXOK_MASK)
> >
> >   /* CAN register bit shift - XCAN_<REG>_<BIT>_SHIFT */
> > @@ -526,6 +527,7 @@ static int xcan_rx(struct net_device *ndev)
> >   	return 1;
> >   }
> >
> > +static void xcan_chip_stop(struct net_device *ndev);
> >   /**
> >    * xcan_err_interrupt - error frame Isr
> >    * @ndev:	net_device pointer
> > @@ -597,7 +599,8 @@ static void xcan_err_interrupt(struct net_device *ndev, u32 isr)
> >   	if (isr & XCAN_IXR_RXOFLW_MASK) {
> >   		stats->rx_over_errors++;
> >   		stats->rx_errors++;
> > -		priv->write_reg(priv, XCAN_SRR_OFFSET, XCAN_SRR_RESET_MASK);
> > +		xcan_chip_stop(ndev);
> > +		xcan_chip_start(ndev);
> >   		if (skb) {
> >   			cf->can_id |= CAN_ERR_CRTL;
> >   			cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
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