[PATCH 1/1] irqchip: irq-gic: forward SGI to itself for cortex-a7 single core

[Fabio Estevam]

Hi Marc,

On Tue, Aug 9, 2016 at 5:54 AM, Marc Zyngier <marc.zyngier at arm.com> wrote:

> From 23ba8b645d219e333a10224d74fb5d8d75d67de2 Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <marc.zyngier at arm.com>
> Date: Tue, 9 Aug 2016 07:50:44 +0100
> Subject: [PATCH] irqchip/gic: Allow self-SGIs for SMP on UP configurations
>
> On systems where a single CPU is present, the GIC may not support
> having SGIs delivered to a target list. In that case, we use the
> self-SGI mechanism to allow the interrupt to be delivered locally.
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
>  drivers/irqchip/irq-gic.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index c2cab57..390fac5 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -769,6 +769,13 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
>         int cpu;
>         unsigned long flags, map = 0;
>
> +       if (unlikely(nr_cpu_ids == 1)) {
> +               /* Only one CPU? let's do a self-IPI... */
> +               writel_relaxed(2 << 24 | irq,
> +                              gic_data_dist_base(&gic_data[0]) + GIC_DIST_SOFTINT);
> +               return;
> +       }
> +
>         raw_spin_lock_irqsave(&irq_controller_lock, flags);

With this patch applied 'reboot' command works fine, but now after
going into suspend mode, it reboots automatically.

# echo mem > /sys/power/state
[  285.299792] PM: Syncing filesystems ... done.
[  285.397549] Freezing user space processes ... (elapsed 0.007 seconds) done.
[  285.412868] Double checking all user space processes after OOM
killer disable... (elapsed 0.000 seconds)
[  285.423597] Freezing remaining freezable tasks ... (elapsed 0.008
seconds) done.
[  285.523882] PM: suspend of devices complete after 78.037 msecs
[  285.529926] PM: suspend devices took 0.090 seconds
[  285.542638] PM: late suspend of devices complete after 7.799 msecs
[  285.557131] PM: noirq suspend of devices complete after 8.105 msecs
[  285.563589] Disabling non-boot CPUs ...


U-Boot 2016.07 (Aug 02 2016 - 17:50:40 -0300)

CPU:   Freescale i.MX6UL rev1.0 at 396 MHz
Reset cause: POR
Board: PICO-IMX6UL-EMMC
DRAM:  256 MiB
MMC:   FSL_SDHC: 0
In:    serial
Out:   serial
Err:   serial
Net:   CPU Net Initialization Failed
No ethernet found.
Hit any key to stop autoboot:  0