From: Nathan Sullivan <nathan.sullivan@ni.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-rt-users@vger.kernel.org, msmucr@gmail.com, bigeasy@linutronix.de
Subject: Re: [PATCH] genirq: Handle force threading of irqs with primary and thread handler
Date: Mon, 21 Sep 2015 10:04:33 -0500 [thread overview]
Message-ID: <20150921150433.GA3460@nathan3500-linux-VM> (raw)
In-Reply-To: <alpine.DEB.2.11.1509211101190.5606@nanos>
On Mon, Sep 21, 2015 at 11:04:31AM +0200, Thomas Gleixner wrote:
> Force threading of interrupts does not deal with interrupts which are
> requested with a primary and a threaded handler. The current policy is
> to leave them alone and let the primary handler run in interrupt
> context, but we set the ONESHOT flag for those interrupts as well.
>
> Kohji Okuno debugged a problem with the SDHCI driver where the
> interrupt thread waits for a hardware interrupt to trigger, which cant
> work well because the hardware interrupt is masked due to the ONESHOT
> flag being set. He proposed to set the ONESHOT flag only if the
> interrupt does not provide a thread handler.
>
> Though that does not work either because these interrupts can be
> shared. So the other interrupt would rightfully get the ONESHOT flag
> set and therefor the same situation would happen again.
>
> To deal with this proper, we need to force thread the primary handler
> of such interrupts as well. That means that the primary interrupt
> handler is treated as any other primary interrupt handler which is not
> marked IRQF_NO_THREAD. The threaded handler becomes a separate thread
> so the SDHCI flow logic can be handled gracefully.
>
> The same issue was reported against 4.1-rt.
>
> Reported-by: Kohji Okuno <okuno.kohji@jp.panasonic.com>
> Reported-By: Michal Šmucr <msmucr@gmail.com>
> Reported-by: Nathan Sullivan <nathan.sullivan@ni.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>
> This requires to revert commit: d04ea10ba1ea 'mmc: sdhci: don't provide
> hard irq handler'
>
Tested on an Intel Bay Trail system with ath6kl SDIO wireless, works fine.
Tested-by: Nathan Sullivan <nathan.sullivan@ni.com>
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prev parent reply other threads:[~2015-09-21 15:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-21 9:04 [PATCH] genirq: Handle force threading of irqs with primary and thread handler Thomas Gleixner
2015-09-21 15:04 ` Nathan Sullivan [this message]
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