linux-kernel - Re: [PATCH] irqchip/gic: restore global interrupts group settings in distributor

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Date:	Wed, 05 Aug 2015 10:59:10 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Anson Huang <Anson.Huang@...escale.com>,
	"rmk+kernel@....linux.org.uk" <rmk+kernel@....linux.org.uk>
CC:	Anson Huang <b20788@...escale.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"jason@...edaemon.net" <jason@...edaemon.net>
Subject: Re: [PATCH] irqchip/gic: restore global interrupts group settings
 in distributor

On 05/08/15 10:17, Anson Huang wrote:
> On Wed, Aug 05, 2015 at 10:12:35AM +0100, Marc Zyngier wrote:
>> Hi Anson,
>>
>> On 05/08/15 17:39, Anson Huang wrote:
>>> In GIC's distributor initializtion, all global interrupts
>>> are set to group 1, however, after suspend/resume with
>>> ARM/GIC power off/on, distributor does NOT restore
>>> these global interrupts group setting, it will cause
>>> system fail to resume.
>>>
>>> This patch adds global interrupts group setting restore
>>> for distributor.
>>>
>>> Signed-off-by: Anson Huang <b20788@...escale.com>
>>> ---
>>>  drivers/irqchip/irq-gic.c | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
>>> index a530d9a..c8fa6ee 100644
>>> --- a/drivers/irqchip/irq-gic.c
>>> +++ b/drivers/irqchip/irq-gic.c
>>> @@ -532,6 +532,16 @@ static void gic_dist_restore(unsigned int gic_nr)
>>>  		writel_relaxed(gic_data[gic_nr].saved_spi_enable[i],
>>>  			dist_base + GIC_DIST_ENABLE_SET + i * 4);
>>>  
>>> +	writel_relaxed(GICD_ENABLE_GRP1, dist_base + GIC_DIST_CTRL);
>>> +
>>> +	/*
>>> +	 * Optionally set all global interrupts to be group 1.
>>> +	 */
>>> +	if (readl_relaxed(dist_base + GIC_DIST_CTRL) & GICD_ENABLE_GRP1) {
>>> +		for (i = 32; i < gic_irqs; i += 32)
>>> +			writel_relaxed(0xffffffff, dist_base + GIC_DIST_IGROUP + i * 4 / 32);
>>> +	}
>>> +
>>>  	writel_relaxed(GICD_ENABLE | GICD_ENABLE_GRP1, dist_base + GIC_DIST_CTRL);
>>>  }
>>>  
>>>
>>
>> I'm afraid you'll have to explain a few more things here.
>>
>> For GICv1/v2, we exclusively use Group0 interrupts when booted in secure
>> mode (i.e. we don't use FIQ yet, but RMK and Daniel Thompson have
>> patches for that). When booted in non-secure, the group configuration is
>> not accessible (it is secure only).
>>
>> So the first case is not applicable yet, and the second one is not
>> possible. Which side are you on?
>>
>> Thanks,
>>
>> 	M.
> 
> Hi, Marc
> 	I may NOT know the history of enabling secure/non-secure of GIC very well, will spend
> some time look into it later, during the upstream of our i.MX6UL's suepnd/resume,
> I found patch(19bcd001 ARM: cobble together FIQ backtracing) break kernel resume function. After
> looking into the gic driver, I saw the dist_inti set all global interrupts to GROUP 1(non-secure), but in
> dist_restore, it does NOT restore those settings, after restoring them, suspend/resume works.

Right, this is the code from Russell and Daniel I was talking about. As
it says in the commit message:

  Cobble the FIQ backtracing together, some of this patch is based on
  some of Daniel Thompson's work.  Experimental, and not for submission
  yet.

So this patch doesn't apply to mainline.

> 	Don't we need to make this GIC distributor settings after resume aligned with before suspend?
> Before suspend, global interrupts are set to non-secure, but after resume, it is by default set to
> secure mode, while cpu controller signal secure interrupts to FIQn, so that is incorrect, not sure
> if my understanding is correct, please correct me if I am wrong.

You're correct that something has to be done. But this should be done as
part of Russell and Daniel FIQ series.

Russell, are you willing to carry that patch (or something similar) as
part of your series?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
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