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    SubjectRe: [PATCH v10 16/21] irqchip: Add GICv2 specific ACPI boot support
    Hey Grant,

    On Wed, Mar 11, 2015 at 06:04:50PM +0000, Grant Likely wrote:
    > On 11 Mar 2015 12:42, "Hanjun Guo" <hanjun.guo@linaro.org> wrote:
    > >
    > > From: Tomasz Nowicki <tomasz.nowicki@linaro.org>
    > >
    > > ACPI kernel uses MADT table for proper GIC initialization. It needs to
    > > parse GIC related subtables, collect CPU interface and distributor
    > > addresses and call driver initialization function (which is hardware
    > > abstraction agnostic). In a similar way, FDT initialize GICv1/2.
    > >
    > > NOTE: This commit allow to initialize GICv1/2 basic functionality.
    > > While now simple GICv2 init call is used, any further GIC features
    > > require generic infrastructure for proper ACPI irqchip initialization.
    > > That mechanism and stacked irqdomains to support GICv2 MSI/virtualization
    > > extension, GICv3/4 and its ITS are considered as next steps.
    > >
    > > CC: Jason Cooper <jason@lakedaemon.net>
    > > CC: Marc Zyngier <marc.zyngier@arm.com>
    > > CC: Thomas Gleixner <tglx@linutronix.de>
    >
    > BTW, Thomas is taking a bit of a break, do he is unlikely to give an ack
    > here in a timely manner. I've not heard from Jason. Personally, I think we
    > can proceed without their ack if everything else is in order (heck, I used
    > to help with the irq subsystem, use me as an ack of you want). The patch is
    > low impact and only had effect for ARM ACPI builds.

    I'm not talking much, but I am tracking and collecting everything for irqchip.
    We do have some other changes in this driver this time around. So it'd be nice
    if I could take this.

    I had reached out to Olof for his thoughts on this and he hasn't had enough
    cycles to look at it. iirc, Marc reviewed a previous version and was happy with
    the changes. My only question I had for Olof I'll put below:

    > > diff --git a/drivers/irqchip/irqchip.c b/drivers/irqchip/irqchip.c
    > > index 0fe2f71..afd1af3 100644
    > > --- a/drivers/irqchip/irqchip.c
    > > +++ b/drivers/irqchip/irqchip.c
    > > @@ -8,6 +8,7 @@
    > > * warranty of any kind, whether express or implied.
    > > */
    > >
    > > +#include <linux/acpi_irq.h>
    > > #include <linux/init.h>
    > > #include <linux/of_irq.h>
    > > #include <linux/irqchip.h>
    > > @@ -26,4 +27,6 @@ extern struct of_device_id __irqchip_of_table[];
    > > void __init irqchip_init(void)
    > > {
    > > of_irq_init(__irqchip_of_table);
    > > +
    > > + acpi_irq_init();
    > > }

    Is this in line with Olof's idea that providing a dtb would override ACPI?

    I have no strong opinion on the matter personally. I haven't been able to
    follow the ACPI discussion as closely as I would have liked, what with the new
    job and all.

    Just let me know and I can pull it in with other GIC changes for this cycle.
    I'll do a topic branch in case other branches need to depend on this.

    thx,
    Jason.


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