linux-kernel - Re: [PATCH] genirq: provide means to retrigger parent

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Date:	Tue, 16 Oct 2012 23:15:02 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Kevin Hilman <khilman@...prootsystems.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] genirq: provide means to retrigger parent

On Tue, Oct 16, 2012 at 03:07:49PM -0700, Kevin Hilman wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
> 
> Attempts to retrigger nested threaded IRQs currently fail because they
> have no primary handler.  In order to support retrigger of nested
> IRQs, the parent IRQ needs to be retriggered.
> 
> To fix, when an IRQ needs to be resent, if the interrupt has a parent
> IRQ and runs in the context of the parent IRQ, then resend the parent.
> 
> Also, handle_nested_irq() needs to clear the replay flag like the
> other handlers, otherwise check_irq_resend() will set it and it will
> never be cleared.  Without clearing, it results in the first resend
> working fine, but check_irq_resend() returning early on subsequent
> resends because the replay flag is still set.
> 
> Problem discovered on ARM/OMAP platforms where a nested IRQ that's
> also a wakeup IRQ happens late in suspend and needed to be retriggered
> during the resume process.
> 
> Reported-by: Kevin Hilman <khilman@...com>
> Tested-by: Kevin Hilman <khilman@...com>
> [khilman@...com: changelog edits, clear IRQS_REPLAY in handle_nested_irq()]
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Umm, we also have the converse situation.  We have platforms where the
resend has to be done from the child IRQ, and the parent must not be
touched.  I hope that doesn't break those.
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