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From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] ide: Fix ata_id_has_dword_io to return DWORD I/O support properly
Date: Fri, 19 Dec 2008 00:13:09 +0100
User-Agent: KMail/1.10.3 (Linux/2.6.28-rc8-next-20081218; KDE/4.1.3; i686; ; )
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>, Jeff Garzik <jeff@garzik.org>,
       Mario Schwalbe <schwalbe@inf.tu-dresden.de>,
       linux-kernel@vger.kernel.org,
       Linux IDE mailing list <linux-ide@vger.kernel.org>
References: <494A5BBF.8000807@inf.tu-dresden.de> <200812182142.16533.bzolnier@gmail.com> <20081218224010.45e3ce55@lxorguk.ukuu.org.uk>
In-Reply-To: <20081218224010.45e3ce55@lxorguk.ukuu.org.uk>
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On Thursday 18 December 2008, Alan Cox wrote:
> > OTOH the current patch is safe even for 2.6.28 (based on years of experience
> > with the check that we had in IDE subsystem) and will fix some libata drivers
> > (pata_legacy, pata_qdi and pata_winbond) to use dword IO on >= ATA-2 devices.
> > 
> > [ In reality this a regression fix for IDE -> libata conversion as it is a
> >   huge performance improvement for the above mentioned DMA-less drivers. ]
> 
> The 32bit PIO support is already queued up and went to Jeff a while ago
> so thats all in hand - its btw a big win on some suprising chipset cases
> including Intel ICH chipsets.

It is a not exactly the same issue as the pata_{legacy,qdi,winbond} one
discussed above.  Anyway cool to see another IDE -> libata regression fixed.

> > Jeff, I would like to merge it through IDE tree since the other patch depends
> > on it but if you want to go ahead and push it to Linus earlier feel free to
> > do it (or I can include it into the next IDE fixes pull request if you like).
> 
> Its still broken. You cannot use the version check for versions below 3.

Hmm, this doesn't seem to be a problem w.r.t. to the patch we are discussing
because in such case ata_id_major_version() will just return 0 and the check
will behave in the identical way as it was before the patch.

> I remain unconvinced we should be looking at it anywhere except specific
> pure ISA cycle pass through hardware and thus it belongs as a helper for
> those drivers not as ata_has_mumble stuff as its not ATA - eide_* maybe.

Sure, we can always improve things further later.  However Mario's patch
is _definitely_ an improvement over the _current_ code.  Don't you agree?

[ There are no alternative patches to consider currently so... ]

Thanks,
Bart
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