linux-kernel - Re: [PATCH] xen: clear IRQ_NOAUTOEN and IRQ

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Date:	Tue, 30 Apr 2013 16:02:42 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Julien Grall <julien.grall@...aro.org>
CC:	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>,
	"patches@...aro.org" <patches@...aro.org>
Subject: Re: [PATCH] xen: clear IRQ_NOAUTOEN and IRQ_NOREQUEST when a VIRQ
 is bound

On Mon, 29 Apr 2013, Julien Grall wrote:
> Reset the IRQ_NOAUTOEN and IRQ_NOREQUEST flags that are enabled by
> default on ARM. If IRQ_NOAUTOEN is set, __setup_irq doesn't call
> irq_startup, that is responsible for calling irq_unmask at startup time.
> As a result event channels remain masked.
> 
> The clear is already made in bind_evtchn_to_irq with commit a8636c0 but was
> missing in bind_virq_to_irq.
> 
> Signed-off-by: Julien Grall <julien.grall@...aro.org>

As in the original commit, you should point out that this change does
not have any effects on x86 (where IRQ_NOREQUEST and IRQ_NOAUTOEN are
cleared by default).

At this point we might as well do this consistently everywhere we
allocate a new evtchn irq, including pirqs and ipis, even though we don't
actually use them on ARM.

If the call to irq_clear_status_flags can be moved earlier, a good place
for it could be xen_irq_init.


>  drivers/xen/events.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index d8cc812..b0ad226 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -994,6 +994,7 @@ int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
>  		WARN_ON(info == NULL || info->type != IRQT_VIRQ);
>  	}
>  
> +	irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
>  out:
>  	mutex_unlock(&irq_mapping_update_lock);

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