From: Pawel Moll <pawel.moll@arm.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Chris Ball <cjb@laptop.org>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
Ulf Hansson <ulf.hansson@stericsson.com>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH] mmc: mmci: Add new VE MMCI variant
Date: Fri, 14 Dec 2012 17:35:45 +0000 [thread overview]
Message-ID: <1355506545.31602.5.camel@hornet> (raw)
In-Reply-To: <20121214171110.GL14363@n2100.arm.linux.org.uk>
On Fri, 2012-12-14 at 17:11 +0000, Russell King - ARM Linux wrote:
> On Fri, Dec 14, 2012 at 03:38:46PM +0000, Pawel Moll wrote:
> > The Versatile Express IOFPGA as shipped on VECD 5.0 (bitfiles v108/208
> > and v116/216) contains a modified version of the PL180 MMCI, with
> > PeriphID Configuration value changed to 0x2.
> >
> > This version adds an optional "hardware flow control" feature. When
> > enabled MMC card clock will be automatically disabled when FIFO is
> > about to over/underflow and re-enabled once the host retrieved some
> > data. This makes the controller immune to over/underrun errors caused
> > by big interrupt handling latencies.
>
> Wrong. It doesn't make it "immune", it just makes it less likely to
> occur - you just need a heavier workload to provoke it.
Why do you think so? The MMC clock is cut off when the FIFO gets full,
so there will be no more data received - no overflow is possible.
Paweł
next prev parent reply other threads:[~2012-12-14 17:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-14 15:38 [PATCH] mmc: mmci: Add new VE MMCI variant Pawel Moll
2012-12-14 17:11 ` Russell King - ARM Linux
2012-12-14 17:35 ` Pawel Moll [this message]
2012-12-14 19:49 ` Linus Walleij
2012-12-14 19:44 ` Linus Walleij
2012-12-21 11:05 ` Ulf Hansson
2013-01-24 12:36 ` Pawel Moll
2013-01-24 12:48 ` Ulf Hansson
2013-01-24 12:59 ` Russell King - ARM Linux
2013-01-24 13:16 ` Ulf Hansson
2013-01-24 17:12 ` Linus Walleij
2013-01-24 20:11 ` Ulf Hansson
2013-01-25 9:35 ` Linus Walleij
2013-01-26 18:53 ` Ulf Hansson
2013-01-24 12:54 ` Pawel Moll
2013-01-24 13:04 ` Ulf Hansson
2013-01-24 13:05 ` Ulf Hansson
2013-01-24 12:57 ` Chris Ball
2013-01-24 13:03 ` Pawel Moll
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