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Message-ID: <20080609130831.GC30971@flint.arm.linux.org.uk>
Date: Mon, 9 Jun 2008 14:08:31 +0100
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Pierre Ossman <drzeus@...eus.cx>
Cc: Nicolas Ferre <nicolas.ferre@...el.com>,
Linux Kernel list <linux-kernel@...r.kernel.org>,
Andrew Victor <linux@...im.org.za>,
Eric BENARD <ebenard@...e.fr>,
ARM Linux Mailing List
<linux-arm-kernel@...ts.arm.linux.org.uk>
Subject: Re: [PATCH 4/7] mmc: at91_mci: add multiwrite switch
On Mon, Jun 09, 2008 at 12:42:49PM +0200, Pierre Ossman wrote:
> On Sun, 1 Jun 2008 15:42:52 +0100
> Russell King - ARM Linux <linux@....linux.org.uk> wrote:
>
> > If Pierre wants to remove the MULTIWRITE flag, I'd like to hear his
> > solution for the pxamci driver, where the only way to ascertain how
> > many bytes were transmitted may be to walk the SG list comparing the
> > DMA pointer with what was in the hardware DMA engine at the time.
> > Maybe.
>
> You set bytes_xfered to 0. As mentioned in my previous mail, I had a
> chat with Jens about this and upper layers can only expect to get the
> lower bound in how many bytes were written. Other hardware/drivers
> already behaves like this so there is no point in crippling the MMC
> layer in an effort to give nicer guarantees.
>
> This is why I asked people to audit their drivers to make sure it's
> the lower bound that's returned, but I've not received much in the way
> of replies.
You won't do from me concerning pxamci - I don't look after it anymore
after one of my MMC cards got eaten by the misbehaving bugger. I don't
think anyone else is looking after it, so that means the driver's
effectively unmaintained.
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