From: Adrian Cox <adrian@humboldt.co.uk>
To: Paulo Afonso Graner Fessel <pafessel@zaz.com.br>
Cc: linux-kernel@vger.kernel.org, hollis@austin.rr.com,
torben.mathiasen@compaq.com
Subject: Re: Probable endianess problem in TLAN driver
Date: Sat, 09 Jun 2001 11:23:20 +0100 [thread overview]
Message-ID: <3B21F918.4090101@humboldt.co.uk> (raw)
In-Reply-To: <3B21A790.63F428CE@zaz.com.br>
Paulo Afonso Graner Fessel wrote:
> [...]
> He said me that these funtions don't address the endianess question, and
> sent me a patch. He said that this probably wouldn't work, but I've
> decided to give a try anyway. Here is the patch:
>
> --- tlan.c.old Thu Jun 7 21:24:25 2001
> +++ tlan.c Thu Jun 7 21:37:42 2001
> @@ -172,6 +172,12 @@
> #include <linux/delay.h>
> #include <linux/spinlock.h>
>
> +#if defined(__powerpc__)
> +#define inw(addr) le32_to_cpu(inw(addr))
> +#define inl(addr) le32_to_cpu(inl(addr))
> +#define outw(val, addr) outw(cpu_to_le32(val), addr)
> +#define outl(val, addr) outl(cpu_to_le32(val), addr)
> +#endif
On ppc the inw, inl, outw, and outl functions already byteswap, so by
adding the extra byteswap you're now passing unswapped data to the chip.
Take a look at include/asm-ppc/io.h and you'll see it uses byte reversed
load and store instructions. Which means that either the chip is running
in a big-endian mode, or that the problem is actually with data
structures placed in host memory.
Often when porting a driver from i386 to ppc all that is required is to
add the cpu_to_le32() macros around data in host memory that the device
accesses, and to remove any #ifdef __powerpc__ code written by people
who don't realise that ppc uses the standard linux pci code.
--
Adrian Cox http://www.humboldt.co.uk/
next prev parent reply other threads:[~2001-06-09 10:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-09 4:35 Probable endianess problem in TLAN driver Paulo Afonso Graner Fessel
2001-06-09 10:23 ` Adrian Cox [this message]
2001-06-09 22:38 ` David S. Miller
2001-06-09 22:58 ` Riley Williams
2001-06-09 23:36 ` David Woodhouse
2001-06-10 6:45 ` David S. Miller
2001-06-09 23:12 ` David S. Miller
2001-06-09 10:11 Mathiasen, Torben
2001-06-09 16:21 ` Paulo Afonso Graner Fessel
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