> -----Original Message-----
> From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
> Sent: 2019年5月18日 1:19
> To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; linux-can@xxxxxxxxxxxxxxx
> Cc: dl-linux-imx <linux-imx@xxxxxxx>; wg@xxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; Aisheng Dong <aisheng.dong@xxxxxxx>
> Subject: Re: [PATCH] can: flexcan: fix deadlock when using self wakeup
>
> On 5/17/19 4:39 AM, Joakim Zhang wrote:
> > As reproted by Sean Nyekjaer bellow:
> > When suspending, when there is still can traffic on the interfaces the
> > flexcan immediately wakes the platform again.
> > As it should :-)
> > But it throws this error msg:
> > [ 3169.378661] PM: noirq suspend of devices failed
> >
> > On the way down to suspend the interface that throws the error message
> > does call flexcan_suspend but fails to call flexcan_noirq_suspend.
> > That means the flexcan_enter_stop_mode is called, but on the way out
> > of suspend the driver only calls flexcan_resume and skips
> > flexcan_noirq_resume, thus it doesn't call flexcan_exit_stop_mode.
> > This leaves the flexcan in stop mode, and with the current driver it
> > can't recover from this even with a soft reboot, it requires a hard
> > reboot.
> >
> > Fixes: de3578c198c6 ("can: flexcan: add self wakeup support")
> >
> > This patch intends to fix the issue, and also add comment to explain
> > the wakeup flow.
> >
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
>
> The existing self wakeup support:
>
> | de3578c198c6 ("can: flexcan: add self wakeup support")
>
> looks broken to me.
>
> According to the data sheet:
>
> > To enter stop mode, the CPU should manually assert a global Stop Mode
> > request (see the CAN1_STOP_REQ and CAN2_STOP_REQ bit in the register
> > IOMUXC_GPR4) and check the acknowledgement asserted by the FlexCAN
> > (see the CAN1_STOP_ACK and CAN2_STOP_ACK in the register
> IOMUXC_GPR4).
> > The CPU must only consider the FlexCAN in Stop Mode when both request
> > and acknowledgement conditions are satisfied.
> you have to poll for the acknowledgement, which is not done in the driver.
> Please fix that first.
Hi Marc,
Patch has sent out to fix it. Thank you!
> As far as I understand the documentation the suspend() and resume functions
> should be symmetric. If they are, you shouldn't need the in_stop_mode hack.
Yes, we don't need in_stop_mode hack if we can let FlexCAN stop mode mechanism be symmetric
in suspend() and resume(). However, it can't be realized as I explained in the patch.
Ang suggestion can provide?
Best Regards,
Joakim Zhang
> regards,
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
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