linux-kernel - Re: [PATCH 03/17] mmc: mmci: Mask IRQs for all variants during runtime suspend

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Date:	Tue, 18 Feb 2014 18:02:38 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Alessandro Rubini <rubini@...pv.it>,
	Linus Walleij <linus.walleij@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Chris Ball <chris@...ntf.net>, Mark Brown <broonie@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
	linux-mmc <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH 03/17] mmc: mmci: Mask IRQs for all variants during
 runtime suspend

On 18 February 2014 17:46, Russell King - ARM Linux
<linux@....linux.org.uk> wrote:
> On Tue, Feb 18, 2014 at 05:36:52PM +0100, Ulf Hansson wrote:
>> If we add SDIO irq support to mmci in future; parts of that
>> implementation includes a re-route of DAT1 to a GPIO irq when entering
>> runtime suspend state. The mmci HW will in runtime suspend state, not
>> be responsible for handling irqs, which is the same as of today.
>
> Note that the "irq thread" in sdio_irq is scheduled for destruction -
> it's buggy when the system is under high load and a driver claims a
> SDIO irq.  Sched people hate it too...

We kind of realized that too, in the early days for ux500. At that
point we converted it to a use a dedicated work queue, which improved
the behaviour, don't remember the details why, but maybe I should
collect the patches and send them out. :-)

Finally we moved to use a separate GPIO irq as a dedicated SDIO irq
line for our cw1200 wlan chip, mostly due to gain a bit of
performance. That happened to simplified the mmci part as well, which
was welcome.

>
> --
> FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
> in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
> Estimate before purchase was "up to 13.2Mbit".
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