linux-kernel - Re: [PATCH v2 1/1] irqchip: exynos-combiner: Save IRQ enable set on suspend

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Message-ID: <557EEDFB.7080502@collabora.co.uk>
Date:	Mon, 15 Jun 2015 17:23:39 +0200
From:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
To:	Sudeep Holla <sudeep.holla@....com>,
	Doug Anderson <dianders@...omium.org>
CC:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	Jason Cooper <jason@...edaemon.net>,
	Chanho Park <parkch98@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Kukjin Kim <kgene@...nel.org>,
	Peter Chubb <peter.chubb@...ta.com.au>,
	Shuah Khan <shuahkhan@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tomasz Figa <tomasz.figa@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 1/1] irqchip: exynos-combiner: Save IRQ enable set
 on suspend

Hello Sudeep,

On 06/15/2015 05:08 PM, Sudeep Holla wrote:
> On 15/06/15 16:00, Javier Martinez Canillas wrote:
>> On 06/15/2015 11:01 AM, Sudeep Holla wrote:
>>> On 15/06/15 08:46, Javier Martinez Canillas wrote:

[...]

>>>
>>> Agreed. But I would suggest also to add MASK_ON_SUSPEND and set_irq_wake
>>> also and then you can restore iff it's non-zero as irq core will take
>>> care of most of the non-wakeup sources. Because I am planning to push
>>
>> I've looking at this and a problem I found is that IIUC the set_irq_wake
>> is not propagated from the the Exynos pinctrl / GPIO driver which is the
>> combiner's external interrupt source so the callback is never called.
>> Which means that right now only the state of the wakeup source IRQs can't
>> be saved since that information is not present.
>>
>> The drivers/pinctrl/samsung/pinctrl-exynos.c driver enables and disables
>> the combiner interrupts but its .irq_set_wake handler only updates the
>> wakeup source mask for the external interrupts but does not call the
>> combiner .set_irq_wake so that should be changed as well.
>>
> 
> Thanks for the looking at this.
>

You are welcome and thanks to you for pointing this out.
 
>> But even for non-wakeup interrupts, I found that they are not enabled when
>> adding the MASK_ON_SUSPEND on my tests. I don't know if that is related
>> to the pinctrl driver missing something else though.
>>
> 
> Even GIC is not masking any interrupt on suspend and if other irqchip or
> drivers are assuming that, it will work fine for now. But once I
> introduce that change in GIC it will break.
> 
>>> MASK_ON_SUSPEND to GIC and it will break this combiner if it assumes the
>>> combiner interrupts are always on in GIC. Implement set_irq_wake as
>>> enable_irq_wake (comb_irq_to_GIC).
>>>
>>
>> Right, but can we do this as a follow-up? S2R is currently broken on these
>> machines and $subject is I think a reasonable small fix that won't introduce
>> any regressions.
>>
> 
> No issues, I just wanted to understand the issue better and also make
> sure we understand that things might break in future once that GIC
> change is introduced. So we already know the reason or atleast have some
> basic understanding as why would it break if it breaks :)
>

Indeed, in the meantime I will continue looking at this to better understand
all the interactions so if something breaks with your changes I may be able
to test / debug and hopefully fix it :)
 
>> To do a more intrusive change, I should better understand the interactions
>> between the Exynos pinctrl / GPIO, interrupt combiner and the GIC and in the
>> meantime S2R will continue to be broken on these platforms unless someone
>> more familiar with all this could point me in the right direction.
>>
> 
> As I said I am fine with this patch for now and I don't want to block it.
>

Thanks a lot, Krzysztof who is one of the Exynos maintainers has also agreed
with the patch so hopefully this can land sooner rather than later.

> Regards,
> Sudeep
> 

Best regards,
Javier
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