Re: [PATCH v2 3/5] gpio: msc313: MStar MSC313 GPIO driver

Re: [PATCH v2 3/5] gpio: msc313: MStar MSC313 GPIO driver

[Marc Zyngier]

On 2020-11-05 15:23, Daniel Palmer wrote:
> Hi Marc,
> 
> On Thu, 5 Nov 2020 at 21:08, Marc Zyngier <maz@kernel.org> wrote:
>> 
>> On 2020-11-05 09:40, Linus Walleij wrote:
>> > On Mon, Oct 19, 2020 at 4:10 PM Daniel Palmer <daniel@0x0f.com> wrote:
>> 
>> [...]
>> 
>> >> +/* The parent interrupt controller needs the GIC interrupt type set
>> >> to GIC_SPI
>> >> + * so we need to provide the fwspec. Essentially
>> >> gpiochip_populate_parent_fwspec_twocell
>> >> + * that puts GIC_SPI into the first cell.
>> >> + */
>> 
>> nit: comment style.
> 
> I've fixed these and some other bits for the v3.
> I've held off on pushing that until the rest of it seemed right.
> 
>> >> +static void *msc313_gpio_populate_parent_fwspec(struct gpio_chip *gc,
>> >> +                                            unsigned int
>> >> parent_hwirq,
>> >> +                                            unsigned int parent_type)
>> >> +{
>> >> +       struct irq_fwspec *fwspec;
>> >> +
>> >> +       fwspec = kmalloc(sizeof(*fwspec), GFP_KERNEL);
>> >> +       if (!fwspec)
>> >> +               return NULL;
>> >> +
>> >> +       fwspec->fwnode = gc->irq.parent_domain->fwnode;
>> >> +       fwspec->param_count = 3;
>> >> +       fwspec->param[0] = GIC_SPI;
>> >> +       fwspec->param[1] = parent_hwirq;
>> >> +       fwspec->param[2] = parent_type;
>> >> +
>> >> +       return fwspec;
>> >> +}
>> >
>> > Clever. Looping in Marc Z so he can say if this looks allright to him.
>> 
>> Yup, this looks correct. However, looking at the bit of the patch that
>> isn't quoted here, I see that msc313_gpio_irqchip doesn't have a
>> .irq_set_affinity callback. Is this system UP only?
> 
> What is in mainline right now is UP only but there are chips with a
> second cortex A7 that I have working in my tree.
> So I will add that in for v3 if I can work out what I should actually
> do there. :)

Probably nothing more than setting the callback to 
irq_chip_set_affinity_parent,
I'd expect.

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

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Re: [PATCH v2 3/5] gpio: msc313: MStar MSC313 GPIO driver

[Linus Walleij]

On Thu, Nov 5, 2020 at 4:43 PM Marc Zyngier <maz@kernel.org> wrote:
> On 2020-11-05 15:23, Daniel Palmer wrote:
> > On Thu, 5 Nov 2020 at 21:08, Marc Zyngier <maz@kernel.org> wrote:

> > >  I see that msc313_gpio_irqchip doesn't have a
> >> .irq_set_affinity callback. Is this system UP only?
> >
> > What is in mainline right now is UP only but there are chips with a
> > second cortex A7 that I have working in my tree.
> > So I will add that in for v3 if I can work out what I should actually
> > do there. :)
>
> Probably nothing more than setting the callback to
> irq_chip_set_affinity_parent,

Hm, is this something all GPIO irqchips used on SMP systems
should be doing? Or just hierarchical ones?

Yours,
Linus Walleij

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Re: [PATCH v2 3/5] gpio: msc313: MStar MSC313 GPIO driver

[Marc Zyngier]

On 2020-11-10 14:02, Linus Walleij wrote:
> On Thu, Nov 5, 2020 at 4:43 PM Marc Zyngier <maz@kernel.org> wrote:
>> On 2020-11-05 15:23, Daniel Palmer wrote:
>> > On Thu, 5 Nov 2020 at 21:08, Marc Zyngier <maz@kernel.org> wrote:
> 
>> > >  I see that msc313_gpio_irqchip doesn't have a
>> >> .irq_set_affinity callback. Is this system UP only?
>> >
>> > What is in mainline right now is UP only but there are chips with a
>> > second cortex A7 that I have working in my tree.
>> > So I will add that in for v3 if I can work out what I should actually
>> > do there. :)
>> 
>> Probably nothing more than setting the callback to
>> irq_chip_set_affinity_parent,
> 
> Hm, is this something all GPIO irqchips used on SMP systems
> should be doing? Or just hierarchical ones?

Probably only the hierarchical ones. I'd expect the non-hierarchical
GPIOs to be muxed behind a single interrupt, which makes it impossible
to move a single GPIO around, and moving the mux interrupt would break
userspace's expectations that interrupts move independently of each 
others.

Thanks,

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

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Re: [PATCH v2 3/5] gpio: msc313: MStar MSC313 GPIO driver

[Linus Walleij]

On Tue, Nov 10, 2020 at 3:19 PM Marc Zyngier <maz@kernel.org> wrote:
> On 2020-11-10 14:02, Linus Walleij wrote:

> >> Probably nothing more than setting the callback to
> >> irq_chip_set_affinity_parent,
> >
> > Hm, is this something all GPIO irqchips used on SMP systems
> > should be doing? Or just hierarchical ones?
>
> Probably only the hierarchical ones. I'd expect the non-hierarchical
> GPIOs to be muxed behind a single interrupt, which makes it impossible
> to move a single GPIO around, and moving the mux interrupt would break
> userspace's expectations that interrupts move independently of each
> others.

I found two suspects and sent patches. I think I might have some
more candidates down in pinctrl. I do have some hierarchical IRQ
that is on UP systems, I suppose these are not affected.

Yours,
Linus Walleij

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Re: [PATCH v2 3/5] gpio: msc313: MStar MSC313 GPIO driver

[Marc Zyngier]

On 2020-11-11 14:09, Linus Walleij wrote:
> On Tue, Nov 10, 2020 at 3:19 PM Marc Zyngier <maz@kernel.org> wrote:
>> On 2020-11-10 14:02, Linus Walleij wrote:
> 
>> >> Probably nothing more than setting the callback to
>> >> irq_chip_set_affinity_parent,
>> >
>> > Hm, is this something all GPIO irqchips used on SMP systems
>> > should be doing? Or just hierarchical ones?
>> 
>> Probably only the hierarchical ones. I'd expect the non-hierarchical
>> GPIOs to be muxed behind a single interrupt, which makes it impossible
>> to move a single GPIO around, and moving the mux interrupt would break
>> userspace's expectations that interrupts move independently of each
>> others.
> 
> I found two suspects and sent patches. I think I might have some
> more candidates down in pinctrl. I do have some hierarchical IRQ
> that is on UP systems, I suppose these are not affected.

Yup, they look good. Feel free to add my Ack to them.
And yes, UP systems are naturally oblivious of interrupt affinity.

Thanks,

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

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