Date: Wed, 21 Jul 2010 14:13:52 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Anton Vorontsov <avorontsov@mvista.com>
Cc: Wolfram Sang <w.sang@pengutronix.de>,
        Albert Herranz <albert_herranz@yahoo.es>,
        Matt Fleming <matt@console-pimps.org>, Ben Dooks <ben-linux@fluff.org>,
        Pierre Ossman <pierre@ossman.eu>, linux-mmc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 0/8] sdhci: Move real work out of an atomic context
Message-Id: <20100721141352.d7993493.akpm@linux-foundation.org>
In-Reply-To: <20100714130728.GA27339@oksana.dev.rtsoft.ru>
References: <20100714130728.GA27339@oksana.dev.rtsoft.ru>
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On Wed, 14 Jul 2010 17:07:28 +0400
Anton Vorontsov <avorontsov@mvista.com> wrote:

> Hi all,
> 
> Currently the sdhci driver does everything in the atomic context.
> And what is worse, PIO transfers are made from the IRQ handler.
> 
> This causes huge latencies (up to 120 ms). On some P2020 SOCs,
> DMA and card detection is broken, which means that kernel polls
> for the card via PIO transfers every second. Needless to say
> that this is quite bad.
> 
> So, this patch set reworks sdhci code to avoid atomic context,
> almost completely. We only do two device memory operations
> in the atomic context, and all the rest is threaded.
> 
> I noticed no throughput drop neither with PIO transfers nor
> with DMA (tested on MPC8569E CPU), while latencies should be
> greatly improved.
> 

The patchset looks good to me, but it'd be nice to hear from the other
people who work on this code, please?

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