linux-kernel - Re: [PATCH 5/5] falconide/q40ide: add ->atapi_*put_bytes and ->ata_*put

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Date:	Mon, 31 Mar 2008 07:53:34 +0200 (CEST)
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
cc:	linux-ide@...r.kernel.org,
	Linux Kernel Development <linux-kernel@...r.kernel.org>,
	Linux/m68k <linux-m68k@...r.kernel.org>,
	Michael Schmitz <schmitz@...ian.org>
Subject: Re: [PATCH 5/5] falconide/q40ide: add ->atapi_*put_bytes and
 ->ata_*put_data methods

On Sun, 30 Mar 2008, Bartlomiej Zolnierkiewicz wrote:
> On Sunday 30 March 2008, Geert Uytterhoeven wrote:
> > On Sun, 30 Mar 2008, Bartlomiej Zolnierkiewicz wrote:
> > > * Add ->atapi_{in,out}put_bytes and ->ata_{in,out}put_data methods to
> > >   falconide and q40ide host drivers (->ata_* methods are implemented on
> > >   top of ->atapi_* methods so they also do byte-swapping now).
> > > 
> > > * Cleanup atapi_{in,out}put_bytes().
> > 
> > Thanks!
> > 
> > One remaining issue (for which the fix has never been submitted upstream so
> > far) with Atari and Q40 is that due to the byteswapped interface, the driveid
> > is also byteswapped, so it has to be unswapped again in ide_fix_driveid().
> 
> My patch causes unswapping for _all_ data coming from the device so I wonder
> whether the ide_fix_driveid() fix is still needed?

I'll give it a try on Aranym...

> [ I now recall some discussion that we shouldn't un-swap fs requests because
>   of how the things were done in the past fs itself is stored byte-swapped on
>   the disk - if this is the case I will recast the patch to pass rq to
>   ->ata_*put_data in ide_pio_sector() and check rq->cmd_type == REQ_TYPE_FS
>   in falconide/q40ide_*put_data() to decide whether to unswap data or not ]

Yes, the data on the disk is stored byte-swapped.
So it's only the drive ID and packet commands that should be swapped.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
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