netdev - Re: [PATCH] firmware: convert acenic driver to request

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Date:	Mon, 16 Jun 2008 18:23:10 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Jes Sorensen <jes@...ined-monkey.org>
Cc:	netdev@...r.kernel.org, jaswinder@...radead.org
Subject: Re: [PATCH] firmware: convert acenic driver to request_firmware()

On Mon, 2008-06-16 at 12:25 -0400, Jes Sorensen wrote:
> Mmmmm,
> 
> I am not particular bothered as to whether or not to put the firmware to
> userspace or not, however has this patch been tested on big endian
> systems? Given that the card is big endian, how is this going to affect
> big endian systems?

We don't have hardware, so haven't been able to test it on either
little-endian or big-endian machines, but we took care to ensure that it
should work on both.

> Honestly, I think it's a bad idea to start messing with the byte order
> of the data for something that happens once at boot time.

Currently, we have the firmware in the host's native endianness -- it's
in the driver in an array of uint32_t. And we just call writel() with
each word of it in turn.

If we provide the firmware via request_firmware(), we don't want to have
separate versions of the firmware files for big-endian and little-endian
hosts. It makes much more sense just to have _one_ version of each
binary file, and either call writel(le32_to_cpu()) for each word, or
writel(be32_to_cpu()).

We chose the former, because it can be simplified to __raw_writel().

Since the CPU on the device is big-endian, I would be amenable to an
argument that we should store the firmware in its native big-endian
form, and load it with writel(be32_to_cpu()) instead.

It doesn't matter much either way, really. 

-- 
dwmw2

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