RE: [PATCH 1/5] ARM: gic: Add hooks for architecture specific extensions

Santosh Shilimkar
2011-01-26T07:22:25Z

> -----Original Message-----
> From: ccross@google.com [mailto:ccross@google.com] On Behalf Of
> Colin Cross
> Sent: Wednesday, January 26, 2011 2:25 AM
> To: Santosh Shilimkar
> Cc: linux-arm-kernel@lists.infradead.org; linux-
> omap@vger.kernel.org; catalin.marinas@arm.com;
> linux@arm.linux.org.uk; linus.ml.walleij@gmail.com; Russell King
> Subject: Re: [PATCH 1/5] ARM: gic: Add hooks for architecture
> specific extensions
>
> On Mon, Jan 24, 2011 at 7:03 PM, Colin Cross <ccross@android.com>
> wrote:
> > On Mon, Jan 24, 2011 at 12:51 AM, Santosh Shilimkar
> > <santosh.shilimkar@ti.com> wrote:
> >> Few architectures combine the GIC with an external interrupt
> controller.
> >> On such systems it may be necessary to update both the GIC
> registers
> >> and the external controller's registers to control IRQ behavior.
> >>
> >> This can be addressed in couple of possible methods.
> >>  1.     Export common GIC routines along with 'struct irq_chip
> gic_chip'
> >>        and allow architectures to have custom function by
> override.
> >>
> >>  2.     Provide architecture specific function pointer hooks
> >>        within GIC library and leave platforms to add the
> necessary
> >>        code as part of these hooks.
> >>
> >> First one might be non-intrusive but have few shortcomings like
> arch needs
> >> to have there own custom gic library. Locks used should be common
> since it
> >> caters to same IRQs etc. Maintenance point of view also it leads
> to
> >> multiple file fixes.
> >>
> >> The second probably is cleaner and portable. It ensures that all
> the
> >> common GIC infrastructure is not touched and also provides archs
> to
> >> address their specific issue.
> >
> > This method would work for most of Tegra's needs, although we
> would
> > need gic_set_type and gic_ack_irq to have arch extensions as well.
> > However, it does not allow for irq_retrigger, which can be
> implemented
> > on Tegra.
>
> irq_retrigger does work with this method, the core IRQ code checks
> for
> a return value if the retrigger was successful. Tegra works with
> your
> patch along with these changes:
>
Great.
Can I fold below changes in my patch and add you ack and tested-by?

> diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
> index 0b6c043..7993f07 100644
> --- a/arch/arm/common/gic.c
> +++ b/arch/arm/common/gic.c
> @@ -90,6 +90,8 @@ static inline unsigned int gic_irq(struct irq_data
> *d)
> static void gic_ack_irq(struct irq_data *d)
> {
> spin_lock(&irq_controller_lock);
> + if (gic_arch_extn.irq_ack)
> + gic_arch_extn.irq_ack(d);
> writel(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI);
> spin_unlock(&irq_controller_lock);
> }
> @@ -161,6 +163,14 @@ static int gic_set_type(struct irq_data *d,
> unsigned int type)
> return 0;
> }
>
> +static int gic_retrigger(struct irq_data *d)
> +{
> + if (gic_arch_extn.irq_retrigger)
> + return gic_arch_extn.irq_retrigger(d);
> +
> + return 0;
> +}
> +
> #ifdef CONFIG_SMP
> static int
> gic_set_cpu(struct irq_data *d, const struct cpumask *mask_val,
> bool force)
> @@ -234,6 +244,7 @@ static struct irq_chip gic_chip = {
> .irq_mask = gic_mask_irq,
> .irq_unmask = gic_unmask_irq,
> .irq_set_type = gic_set_type,
> + .irq_retrigger = gic_retrigger,
> #ifdef CONFIG_SMP
> .irq_set_affinity = gic_set_cpu,
> #endif
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