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

Sudeep Holla
2015-06-15T15:08:44Z

On 15/06/15 16:00, Javier Martinez Canillas wrote:
> Hello Sudeep,
>
> On 06/15/2015 11:01 AM, Sudeep Holla wrote:
>>
>>
>> On 15/06/15 08:46, Javier Martinez Canillas wrote:
>> [...]
>>
>>>
>>> Sudeep, so we may need something like $subject after all from Doug's
>>> explanations since the combiner chip state is lost during a S2R. I know
>>> that it adds more duplicated code (others irqchip drivers do the same)
>>> and it may not scale well if a chip has many registers but is the best
>>> solution I could came with.
>>>
>>
>> OK
>>
>>> If you have a suggestion for a better alternative, I can give a try and
>>> write the patch. But I think $subject could also land to fix this issue
>>> since is a very non intrusive change and later can be changed once the
>>> irqchip core supports this use case.
>>>
>>
>> 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.

> 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 :)

> 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.

Regards,
Sudeep