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Date: Wed, 27 Nov 2019 10:58:06 +0100 From: Sean Nyekjaer <sean@...nix.com> To: Joakim Zhang <qiangqing.zhang@....com>, "mkl@...gutronix.de" <mkl@...gutronix.de>, "linux-can@...r.kernel.org" <linux-can@...r.kernel.org> Cc: dl-linux-imx <linux-imx@....com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org> Subject: Re: [PATCH V2 1/4] can: flexcan: fix deadlock when using self wakeup On 27/11/2019 06.56, Joakim Zhang wrote: > From: Sean Nyekjaer <sean@...nix.com> > > 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. > > This patch can fix deadlock when using self wakeup, it happenes to be > able to fix another issue that frames out-of-order in first IRQ handler > run after wakeup. > > In wakeup case, after system resume, frames received out-of-order in > first IRQ handler, the problem is wakeup latency from frame reception to > IRQ handler is much bigger than the counter overflow. This means it's > impossible to sort the CAN frames by timestamp. The reason is that controller > exits stop mode during noirq resume, then it can receive the frame immediately. > If noirq reusme stage consumes much time, it will extend interrupt response > time. So exit stop mode during resume stage instead of noirq resume can > fix this issue. > > Fixes: de3578c198c6 ("can: flexcan: add self wakeup support") > Signed-off-by: Sean Nyekjaer <sean@...nix.com> > Signed-off-by: Joakim Zhang <qiangqing.zhang@....com> Tested-by: Sean Nyekjaer <sean@...nix.com> > ------ > ChangeLog: > V1->V2: no change. > --- > drivers/net/can/flexcan.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c > index 2efa06119f68..2297663cacb2 100644 > --- a/drivers/net/can/flexcan.c > +++ b/drivers/net/can/flexcan.c > @@ -134,8 +134,7 @@ > (FLEXCAN_ESR_ERR_BUS | FLEXCAN_ESR_ERR_STATE) > #define FLEXCAN_ESR_ALL_INT \ > (FLEXCAN_ESR_TWRN_INT | FLEXCAN_ESR_RWRN_INT | \ > - FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT | \ > - FLEXCAN_ESR_WAK_INT) > + FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT) > > /* FLEXCAN interrupt flag register (IFLAG) bits */ > /* Errata ERR005829 step7: Reserve first valid MB */ > @@ -960,6 +959,12 @@ static irqreturn_t flexcan_irq(int irq, void *dev_id) > > reg_esr = priv->read(®s->esr); > > + /* ACK wakeup interrupt */ > + if (reg_esr & FLEXCAN_ESR_WAK_INT) { > + handled = IRQ_HANDLED; > + priv->write(reg_esr & FLEXCAN_ESR_WAK_INT, ®s->esr); > + } > + > /* ACK all bus error and state change IRQ sources */ > if (reg_esr & FLEXCAN_ESR_ALL_INT) { > handled = IRQ_HANDLED; > @@ -1722,6 +1727,9 @@ static int __maybe_unused flexcan_resume(struct device *device) > netif_start_queue(dev); > if (device_may_wakeup(device)) { > disable_irq_wake(dev->irq); > + err = flexcan_exit_stop_mode(priv); > + if (err) > + return err; > } else { > err = pm_runtime_force_resume(device); > if (err) > @@ -1767,14 +1775,9 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device) > { > struct net_device *dev = dev_get_drvdata(device); > struct flexcan_priv *priv = netdev_priv(dev); > - int err; > > - if (netif_running(dev) && device_may_wakeup(device)) { > + if (netif_running(dev) && device_may_wakeup(device)) > flexcan_enable_wakeup_irq(priv, false); > - err = flexcan_exit_stop_mode(priv); > - if (err) > - return err; > - } > > return 0; > } >
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