From: Anti Sullin <anti.sullin@artecdesign.ee>
To: Harro Haan <hrhaan@gmail.com>
Cc: Ryan Mallon <ryan@bluewatersys.com>,
Remy Bohmer <linux@bohmer.net>,
Andrew Victor <avictor.za@gmail.com>,
David Brownell <dbrownell@users.sourceforge.net>,
H Hartley Sweeten <hartleys@visionengravers.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [patch v2 1/2] at91_udc.c read_fifo timing issue
Date: Mon, 01 Feb 2010 00:34:44 +0200 [thread overview]
Message-ID: <4B660584.7020302@artecdesign.ee> (raw)
In-Reply-To: <20100129162155.709756286@gmail.com>>
Harro Haan wrote:
> This solves the read_fifo timing issue for example seen with CDC
Ethernet.
[...]
Still this bug not fixed?
I sent almost the same fix and a lot of debug info with description of
the issue and the critical path of the timing to linux-arm-kernel on
2009-03-25 (
http://lists.arm.linux.org.uk/lurker/message/20090325.150843.f515c02f.en.html
) and we had an off-list discussion with David Brownell about another
udc patch on 2009-06-19 that later turned out to be the same issue.
This fix has solved the problems on our devices and we've been using it
for almost a year now.
About Harro's patch:
* why are the marker1 and marker2 comments necessary to be included?
* maybe you should just link to the mailing list and/or move the long
comment to patch description instead adding a page-long comment to code;
just leave a small comment to explain why the work-around is needed so
that nobody would optimize it away?
* Is the error check and warning message necessary after we've got rid
of the problem? Won't it add problems - as I found out, the first csr
read (that comes too early) may return bogus data, you should not use
its result at all.
--
Anti Sullin
Embedded Software Engineer
Artec Design LLC
Teaduspargi 6/2, 12618, Tallinn, Estonia
http://www.artecdesign.ee
next prev parent reply other threads:[~2010-01-31 23:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20100129162029.998540038@gmail.com>
[not found] ` <20100129162155.709756286@gmail.com>
2010-01-29 17:04 ` [patch v2 1/2] at91_udc.c read_fifo timing issue Remy Bohmer
2010-01-31 20:08 ` Ryan Mallon
2010-01-31 22:34 ` Anti Sullin [this message]
[not found] ` <20100129162155.824407360@gmail.com>
2010-01-29 17:27 ` [patch v2 2/2] at91_udc.c use spinlocks instead of local_irq_xxx H Hartley Sweeten
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