Linux Serial subsystem development

* Re: [PATCH v6 1/6] irqchip/mtk-sysirq: support 4 interrupt parameters for sysirq
From: Marc Zyngier @ 2019-02-11  8:50 UTC (permalink / raw)
  To: Seiya Wang
  Cc: Matthias Brugger, Erin Lo, Rob Herring, Mark Rutland,
	Thomas Gleixner, Jason Cooper, Greg Kroah-Hartman, Stephen Boyd,
	devicetree, srv_heupstream, linux-kernel, linux-serial,
	linux-mediatek, linux-arm-kernel, yingjoe.chen, mars.cheng,
	eddie.huang, linux-clk
In-Reply-To: <1549866929.22817.20.camel@mtksdccf07>

On Mon, 11 Feb 2019 06:35:29 +0000,
Seiya Wang <seiya.wang@mediatek.com> wrote:
> 
> On Thu, 2019-02-07 at 15:52 +0000, Marc Zyngier wrote:
> > On 07/02/2019 15:47, Marc Zyngier wrote:
> > > On 07/02/2019 15:20, Matthias Brugger wrote:
> > >>
> > >>
> > >> On 24/01/2019 09:07, Erin Lo wrote:
> > >>> From: Seiya Wang <seiya.wang@mediatek.com>
> > >>>
> > >>> To support partitioned PPIs, 4 interrupt parameters should be valid
> > >>> for sysirq.
> > >>>
> > >>> Signed-off-by: Seiya Wang <seiya.wang@mediatek.com>
> > >>> Signed-off-by: Erin Lo <erin.lo@mediatek.com>
> > >>> ---
> > >>>  drivers/irqchip/irq-mtk-sysirq.c | 4 ++--
> > >>>  1 file changed, 2 insertions(+), 2 deletions(-)
> > >>>
> > >>> diff --git a/drivers/irqchip/irq-mtk-sysirq.c b/drivers/irqchip/irq-mtk-sysirq.c
> > >>> index 90aaf19..282736a 100644
> > >>> --- a/drivers/irqchip/irq-mtk-sysirq.c
> > >>> +++ b/drivers/irqchip/irq-mtk-sysirq.c
> > >>> @@ -81,7 +81,7 @@ static int mtk_sysirq_domain_translate(struct irq_domain *d,
> > >>>  				       unsigned int *type)
> > >>>  {
> > >>>  	if (is_of_node(fwspec->fwnode)) {
> > >>> -		if (fwspec->param_count != 3)
> > >>> +		if (fwspec->param_count != 3 && fwspec->param_count != 4)
> > >>
> > >> Where is this 4th parameter used?
> > > 
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.txt#n14
> > Sorry, I fired Send way too early.
> > 
> > What I wanted to add is that it is not clear to me why this change would
> > be required here, as this driver only supports SPIs. It could be fixed
> > by just relaxing the binding itself.
> > 
> > Thanks,
> > 
> > 	M.
> 
> Do you mean that we should change #interrupt-cells back to 3 for sysirq
> and remove the 4th parameters of every spi interrupts in mt8183.dtsi
> (i.e. 3 parameters for spi, 4 for ppi) such that we can discard this
> patch?

It is more subtle than that:

- PPIs must have the affinity parameter in their int-spec (since you
  need that for the PMU)

- SPIs that are directly routed to the GIC must also have the affinity
  parameter (although set to zero).

- SPIs that are routed via the sysirq block (or any other) can use the
  3 parameter variant, as they are not resolved in the context of the
  GIC, but in that of the sysirq.

But in short, yes. You should be able to drop this patch altogether.

> If yes, we may need some time to verify the change before resending the
> patch.

That's absolutely fine.

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.

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