linux-kernel - Re: [PATCH] irq: Add a new IRQF_ACK_BEFORE

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Date:	Thu, 13 Mar 2014 14:32:56 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
cc:	Hans de Goede <hdegoede@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Carlo Caione <carlo.caione@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Sekhar Nori <nsekhar@...com>,
	Kevin Hilman <khilman@...prootsystems.com>
Subject: Re: [PATCH] irq: Add a new IRQF_ACK_BEFORE_UNMASK irq flag

On Thu, 13 Mar 2014, Sebastian Andrzej Siewior wrote:

> * Thomas Gleixner | 2014-03-12 11:38:24 [+0100]:
> 
> >Untested patch below.
> Tested-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> 
> on DA850 / OMAP-L138. Without:
>   59:        560   cp_intc  ohci_hcd:usb2
> with the patch
>   59:        280   cp_intc  ohci_hcd:usb2
> 
> that makes a difference of 280 interrupts. Prior the patch each
> interrupt was handled twice and returned once with IRQ_HANDLED and the
> second time with IRQ_NONE. With the proper EOI ack I don't see the
> IRQ_NONE anymore.

Right. The documentation of L138 clearly says, that you need to ack
the interrupt AFTER the handler has run. But the driver uses
handle_edge_irq, which acks BEFORE the handler has run.

Quality stuff.

Thanks,

	tglx






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