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

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Message-Id: <200803302134.42569.bzolnier@gmail.com>
Date:	Sun, 30 Mar 2008 21:34:42 +0200
From:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
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


Hi,

On Sunday 30 March 2008, Geert Uytterhoeven wrote:
> 	Hi Bart,
> 
> 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 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 ]

Thanks,
Bart

> Here's a very old and unclean but working patch:
> 
> --- a/drivers/ide/ide-iops.c
> +++ b/drivers/ide/ide-iops.c
> @@ -284,6 +284,23 @@ void ide_fix_driveid (struct hd_driveid 
>  	int i;
>  	u16 *stringcast;
>  
> +#ifdef __mc68000__
> +	if (!MACH_IS_AMIGA && !MACH_IS_MAC && !MACH_IS_Q40 && !MACH_IS_ATARI)
> +		return;
> +
> +#ifdef M68K_IDE_SWAPW
> +	if (M68K_IDE_SWAPW) {	/* fix bus byteorder first */
> +		u_char *p = (u_char *)id;
> +		u_char t;
> +		for (i = 0; i < 512; i += 2) {
> +			t = p[i];
> +			p[i] = p[i+1];
> +			p[i+1] = t;
> +		}
> +	}
> +#endif
> +#endif /* __mc68000__ */
> +
>  	id->config         = __le16_to_cpu(id->config);
>  	id->cyls           = __le16_to_cpu(id->cyls);
>  	id->reserved2      = __le16_to_cpu(id->reserved2);
> 
> Note that include/asm-m68k/ide.h has
> 
>     #define M68K_IDE_SWAPW  (MACH_IS_Q40 || MACH_IS_ATARI)
> 
> 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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