Re: [PATCH 05/11] irqchip / gic: Add stacked irqdomain support for ACPI based GICv2 init

[Hanjun Guo]

On 06/11/2015 12:27 AM, Marc Zyngier wrote:
> On 18/05/15 13:59, Hanjun Guo wrote:
> > Introduce acpi_irq_domain for GICv2 core domain instead of referring
> > to the irq_default_domain, based on that, pass gsi as the argument and
> > get the gsi in gic_irq_domain_alloc() to add stacked irqdomain support
> > for ACPI based GICv2 init.
> >
> > Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> > ---
> >   drivers/acpi/gsi.c                   | 28 +++++++++++++---------------
> >   drivers/irqchip/irq-gic.c            | 32 +++++++++++++++++---------------
> >   include/linux/irqchip/arm-gic-acpi.h |  2 ++
> >   3 files changed, 32 insertions(+), 30 deletions(-)
> >
> > diff --git a/drivers/acpi/gsi.c b/drivers/acpi/gsi.c
> > index 38208f2..55b5f31 100644
> > --- a/drivers/acpi/gsi.c
> > +++ b/drivers/acpi/gsi.c
> > @@ -3,6 +3,7 @@
> >    *
> >    * Copyright (C) 2015 ARM Ltd.
> >    * Author: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > + *         Hanjun Guo <hanjun.guo@xxxxxxxxxx> for stacked irqdomains support
> >    *
> >    * This program is free software; you can redistribute it and/or modify
> >    * it under the terms of the GNU General Public License version 2 as
> > @@ -13,6 +14,8 @@
> >   #include <linux/irqdomain.h>
> >
> >   enum acpi_irq_model_id acpi_irq_model;
> > +/* ACPI core domian pointing to GICv2/3 core domain */
> > +struct irq_domain *acpi_irq_domain __read_mostly;
>
> How is a single domain pointer going to work when you will have several
> domains (GICv2m, ITS)?

This acpi_irq_domain is the core domain which is the parent domain
of GICv2m or ITS.

acpi_irq_domain points to GICv2 or GICv3 domain when the GIC
is initialized.

> Crucially, how are you going to perform the
> matching of a device with its irq domain?

since every ITS will have a domain, and there is a mapping
from device id to ITS ID in IORT table, then we can match the
device with the ITS irq domain, does it make sense?

Thanks
Hanjun
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