linux-kernel - Re: [PATCH] irqchip/atmel-aic5: handle suspend to RAM

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Message-ID: <20170410123053.sqnqovvlgarevyzu@piout.net>
Date:   Mon, 10 Apr 2017 14:30:53 +0200
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Jason Cooper <jason@...edaemon.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] irqchip/atmel-aic5: handle suspend to RAM

On 09/04/2017 at 13:13:33 +0100, Marc Zyngier wrote:
> On Thu, 6 Apr 2017 18:17:53 +0200
> Alexandre Belloni <alexandre.belloni@...e-electrons.com> wrote:
> 
> > On sama5d2, VDD core may be cut while suspending to RAM. This means the
> > AIC5 registers content is lost. Restore it at resume time.
> > 
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> > ---
> >  drivers/irqchip/irq-atmel-aic5.c | 17 +++++++++++++++--
> >  1 file changed, 15 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/irqchip/irq-atmel-aic5.c b/drivers/irqchip/irq-atmel-aic5.c
> > index 2a624d87a035..ddbf60251b0e 100644
> > --- a/drivers/irqchip/irq-atmel-aic5.c
> > +++ b/drivers/irqchip/irq-atmel-aic5.c
> > @@ -150,6 +150,8 @@ static int aic5_set_type(struct irq_data *d, unsigned type)
> >  }
> >  
> >  #ifdef CONFIG_PM
> > +u32 smr_cache[128];
> 
> Two things:
> 
> - Why isn't this array static?
> - Why is the size hard-coded to 128, while the loops below are based on
>   the domain revmap_size.
> 
> > +
> >  static void aic5_suspend(struct irq_data *d)
> >  {
> >  	struct irq_domain *domain = d->domain;
> > @@ -159,6 +161,11 @@ static void aic5_suspend(struct irq_data *d)
> >  	int i;
> >  	u32 mask;
> >  
> > +	for (i = 0; i < domain->revmap_size; i++) {
> > +		irq_reg_writel(bgc, i, AT91_AIC5_SSR);
> > +		smr_cache[i] = irq_reg_readl(bgc, AT91_AIC5_SMR);
> > +	}
> > +
> 
> This seem to affect more than just the sama5d2 part. Is that expected?
> 

I'll send v2 addressing your comments shortly. The answer is that it
works on all the SoCs. It was simply not needed before. I'll try to come
up with a solution only affecting sama5d2 anyway.

The best would be to be able to know whether will be cut or not but it
is not currently possible with the PM core.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com