On 01.06.2021 08:50:28, Torin Cooper-Bennun wrote:
> On Wed, May 26, 2021 at 05:15:59PM +0200, Marc Kleine-Budde wrote:
> > On 26.05.2021 13:47:47, Torin Cooper-Bennun wrote:
> > > Handle power, transceiver and SPI failures by printing a useful error
> > > message (multiple simultaneous failures are not logged) and disabling
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >
> > Is this a limitation of your code or the tcan core?
>
> My code doesn't print an error message for every handled interrupt, only
> the first, because it's very rare to see more than one. Perhaps it's
> prudent to print a line for each handled interrupt just in case.
Yes, please make it so.
> > > static irqreturn_t tcan4x5x_handle_dev_interrupts(struct m_can_classdev *cdev,
> > > bool clear_only)
> > > {
> > > - tcan4x5x_clear_interrupts(cdev);
> > > + struct tcan4x5x_priv *priv = cdev_to_priv(cdev);
> > > + int err = 0;
> > > + irqreturn_t handled = IRQ_NONE;
> >
> > nitpick: please make "int err" the last.
>
> ACK
>
> >
> > > +
> > > + if (!clear_only) {
> > > + u32 ir = 0;
> > > + const char *fail_str = "";
> >
> > nitpick: please make the u32 the last.
>
> ACK
>
> > > + else if (ir & TCAN4X5X_CANDOM_INT_EN)
> > > + fail_str = "CAN stuck dominant (CANDOM)";
> >
> > The error message suggests, that this error can be triggered by messing
> > around with the CAN high/low wires. I'm not sure if it's a good idea to
> > shutdown the driver in this case.
>
> ACK, but I need to test whether the device stays functional without CPU
> intervention after CANDOM is asserted.
- Does IRQ line stay asserted if the CAN lines are still stuck dominant?
If yes, this would result in an IRQ storm, which we don't want to have.
If you/we want to handle this in a "proper" way, send a CAN error frame [1],
mask this interrupt, setup a timer/workqueue/etc and unmask it after
some 100ms.
[1] But I'm not sure if we have proper values for stuck dominant yet.
https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/can/error.h#L110
- What happens if the stuck dominant condition is gone?
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
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