Date: Mon, 9 Jun 2008 14:08:31 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Pierre Ossman <drzeus@drzeus.cx>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>,
       Linux Kernel list <linux-kernel@vger.kernel.org>,
       Andrew Victor <linux@maxim.org.za>, Eric BENARD <ebenard@free.fr>,
       ARM Linux Mailing List 
	<linux-arm-kernel@lists.arm.linux.org.uk>
Subject: Re: [PATCH 4/7] mmc: at91_mci: add multiwrite switch
Message-ID: <20080609130831.GC30971@flint.arm.linux.org.uk>
References: <483FE9E7.7020707@atmel.com> <483FEE58.5000500@atmel.com> <20080601144251.GS5818@flint.arm.linux.org.uk> <20080609124249.349995df@mjolnir.drzeus.cx>
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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@arm.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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