linux-kernel - Re: [PATCH 1/1] ahci: Do not receive interrupts sent by dummy ports

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Message-ID: <20140418195650.GJ23576@htj.dyndns.org>
Date:	Fri, 18 Apr 2014 15:56:50 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Alexander Gordeev <agordeev@...hat.com>
Cc:	linux-kernel@...r.kernel.org, David Milburn <dmilburn@...hat.com>,
	linux-ide@...r.kernel.org
Subject: Re: [PATCH 1/1] ahci: Do not receive interrupts sent by dummy ports

On Thu, Apr 17, 2014 at 06:06:15PM +0200, Alexander Gordeev wrote:
> In multiple MSI mode all AHCI ports (including dummy) get
> assigned separate MSI vectors and (as result of execution
> pci_enable_msi_exact() function) separate IRQ numbers,
> (mapped to the MSI vectors).
> 
> Therefore, although interrupts from dummy ports are not
> desired they are still enabled. We do not request IRQs
> for dummy ports, but that only means we do not assign
> AHCI-specific ISRs to corresponding IRQ numbers.
> 
> As result, dummy port interrupts still could come and
> traverse all the way from the PCI device to the kernel,
> causing unnecessary overhead.
> 
> This update disables IRQs for dummy ports and prevents
> the described issue.
> 
> Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: David Milburn <dmilburn@...hat.com>
> Cc: linux-ide@...r.kernel.org

Applied to libata/for-3.15-fixes w/ David's tested-by added.

Thanks.

-- 
tejun
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