(EXT) Re: [PATCH 1/1] irqchip/irq-imx-gpcv2: Disable cpuidle on imx8mq

[Alexander Stein]

Am Mittwoch, dem 01.12.2021 um 12:21 +0100 schrieb Martin Kepplinger:
> Am Freitag, dem 05.11.2021 um 10:55 +0100 schrieb Alexander Stein:
> > Due to errata e11171 sleeping CPUs cannot be woken up by IPIs.
> > 
> > Signed-off-by: Alexander Stein <
> > alexander.stein at ew.tq-group.com
> > >
> > ---
> > With reference to [1] cpuidle is broken on imx8mq with no
> > workaround
> > available in mainline, probably never will.
> > In order to avoid to avoid booting and deadlocking imx8mq systems,
> > disable cpuidle unconditionally.
> > I was wondering which driver would be the best to add this code (it
> > would work pretty much everywhere), but I opted for irq-imx-gpcv2
> > as
> > this is used imx8mq (and imx7d) only.
> > I also added '#ifdef CONFIG_CPU_IDLE' to avoid this warning when
> > cpuidle
> > support is not compiled in, although cpuidle support without the
> > psci
> > driver will this issue this warning. But using
> > CONFIG_ARM_PSCI_CPUIDLE
> > here looks odd to me.
> > 
> > [1] 
> > http://lists.infradead.org/pipermail/linux-arm-kernel/2021-November/694075.html
> > 
> 
> hi Alexander,
> 
> Did you see the deadlocking problems you mention? What I see in
> imx8mq
> is simply having the WFI cpuidle state, and no other one (the "real"
> one where wakeup is broken dua to the mentioned erratum).

Hi Martin,

well it was not a deadlock in the sense that everything stucked.
Instead my NFS boot failed. The backlog showed me that one idling core
was holding some lock while tried to get that lock. But the idling core
was not woken up due to this errata.
Unfortunately I don't see them with on next-20211208. This might be due
to a huge CPU usage & interrupt load on various kworker threads.
Preventing from going to WFI, I assume.
I'll check again once this is fixed.

thanks,
Alexander

> >  drivers/irqchip/irq-imx-gpcv2.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/drivers/irqchip/irq-imx-gpcv2.c b/drivers/irqchip/irq-
> > imx-gpcv2.c
> > index 5b5a365dbd5e..6a2fc3c7df67 100644
> > --- a/drivers/irqchip/irq-imx-gpcv2.c
> > +++ b/drivers/irqchip/irq-imx-gpcv2.c
> > @@ -3,6 +3,7 @@
> >   * Copyright (C) 2015 Freescale Semiconductor, Inc.
> >   */
> >  
> > +#include <linux/cpuidle.h>
> >  #include <linux/of_address.h>
> >  #include <linux/of_irq.h>
> >  #include <linux/slab.h>
> > @@ -221,6 +222,13 @@ static int __init
> > imx_gpcv2_irqchip_init(struct
> > device_node *node,
> >  
> >         core_num = (unsigned long)id->data;
> >  
> > +#ifdef CONFIG_CPU_IDLE
> > +       if (of_machine_is_compatible("fsl,imx8mq")) {
> > +               pr_warn("Disabling cpuidle on i.MX8M due to errata
> > e11171\n");
> > +               disable_cpuidle();
> > +       }
> > +#endif
> > +
> >         parent_domain = irq_find_host(parent);
> >         if (!parent_domain) {
> >                 pr_err("%pOF: unable to get parent domain\n",
> > node);
> 
> 
>