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    SubjectRe: [PATCH WIP 6/6] xen/arm: enable evtchn irqs
    On Fri, Jul 13, 2012 at 06:14:33PM +0100, Stefano Stabellini wrote:
    > On Mon, 9 Jul 2012, Konrad Rzeszutek Wilk wrote:
    > > On Fri, Jun 22, 2012 at 05:14:45PM +0100, Stefano Stabellini wrote:
    > > > On ARM irqs are not enabled by default:
    > >
    > > Which IRQs? Xen IRQs? Linux IRQs?
    >
    > Linux IRQs
    >
    >
    > > > - call enable_percpu_irq for IRQ_EVTCHN_CALLBACK;
    > >
    > > Why do we want to do that?
    >
    > drivers are supposed to call enable_irq after request_irq, however on
    > x86 we could get away without it because Linux irqs are enabled by
    > default (see below)
    >
    >
    > > > - set the IRQF_VALID flag for the other irqs bound to evtchns. It causes
    > > > IRQ_NOAUTOEN to be set and as a consequence irq_unmask is going to be
    > > > called when a xenbus driver calls request_irq.
    > >
    > > Can you explain in more details why we need that?
    >
    > If _IRQ_NOAUTOEN is set, irq_settings_can_autoenable returns false and
    > __setup_irq doesn't call irq_startup.
    >
    > IRQ_NOAUTOEN is set by default by set_irq_flags on ARM, but not on x86.

    OK, please include those questions/answers in the git commit and
    repost.

    >
    >
    >
    > > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
    > > > ---
    > > > drivers/xen/events.c | 3 +++
    > > > 1 files changed, 3 insertions(+), 0 deletions(-)
    > > >
    > > > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
    > > > index 0132505..ca92755 100644
    > > > --- a/drivers/xen/events.c
    > > > +++ b/drivers/xen/events.c
    > > > @@ -53,6 +53,7 @@
    > > > #include <xen/interface/hvm/params.h>
    > > > #include <xen/interface/physdev.h>
    > > > #include <xen/interface/sched.h>
    > > > +#include <asm/hw_irq.h>
    > > >
    > > > /*
    > > > * This lock protects updates to the following mapping and reference-count
    > > > @@ -827,6 +828,7 @@ int bind_evtchn_to_irq(unsigned int evtchn)
    > > >
    > > > xen_irq_info_evtchn_init(irq, evtchn);
    > > > }
    > > > + set_irq_flags(irq, IRQF_VALID);
    > > >
    > > > out:
    > > > mutex_unlock(&irq_mapping_update_lock);
    > > > @@ -1751,6 +1753,7 @@ int __init xen_init_IRQ_arm(void)
    > > > if (rc) {
    > > > printk(KERN_ERR "Error requesting IRQ %d\n", IRQ_EVTCHN_CALLBACK);
    > > > }
    > > > + enable_percpu_irq(IRQ_EVTCHN_CALLBACK, 0);
    > > > return rc;
    > > > }
    > > > core_initcall(xen_init_IRQ_arm);
    > > > --
    > > > 1.7.2.5
    > > >
    > > > --
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    > > > the body of a message to majordomo@vger.kernel.org
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    > >


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