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From: "Arnd Bergmann" <arnd@kernel.org>
To: "Greg Ungerer" <gerg@kernel.org>, linux-m68k@lists.linux-m68k.org
Cc: linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org,
	linux-can@vger.kernel.org, linux-spi@vger.kernel.org,
	"Vladimir Oltean" <olteanv@gmail.com>,
	"Angelo Dureghello" <adureghello@baylibre.com>
Subject: Re: [RFC 4/4] m68k: coldfire: fix non-standard readX()/writeX() functions
Date: Thu, 07 May 2026 14:59:30 +0200	[thread overview]
Message-ID: <4a617879-5147-4595-b6ce-ef3391b936d9@app.fastmail.com> (raw)
In-Reply-To: <fdd6fc14-f607-4186-8db4-25de973ac322@kernel.org>

On Thu, May 7, 2026, at 14:43, Greg Ungerer wrote:
> On 7/5/26 05:12, Arnd Bergmann wrote:
>> On Wed, May 6, 2026, at 16:26, Greg Ungerer wrote:
>> 
>> I would suggest marking these as explicit BIG_ENDIAN rather than
>> NATIVE_ENDIAN. The effect should be the same since coldfire CPUs
>> cannot run little-endian code, but the way that hardware usually
>> works is that the endianess is fixed at the bus level to one way
>> or the other. NATIVE_ENDIAN to me implies that the registers
>> have configurable endianess that is switched along with the CPU
>> mode.
>
> Ok, will change. I chose native endian in this case since the regmap config
> entry used for the m5441x family is also used by the vf610 devce (which looks
> to be an ARM imx SoC). So it will need a duplicate setup with those endian
> flags set to BIG_ENDIAN. But that is no problem.

Sounds good. In this case, splitting it up is technically even required,
because you can run a big-endian ARMv7 kernel on vf610, so the vf610
entry has to use little-endian registers rather than native.

I don't think anyone has run big-endian kernels on vf610, though I have
heard of users testing them successfully on i.MX6.

      Arnd

  reply	other threads:[~2026-05-07 12:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20260506142644.3234270-2-gerg@kernel.org>
2026-05-06 14:26 ` [RFC 4/4] m68k: coldfire: fix non-standard readX()/writeX() functions Greg Ungerer
2026-05-06 16:14   ` Frank Li
2026-05-06 19:12   ` Arnd Bergmann
2026-05-07 12:43     ` Greg Ungerer
2026-05-07 12:59       ` Arnd Bergmann [this message]
2026-05-07 13:30   ` Marc Kleine-Budde
2026-05-07 14:33     ` Greg Ungerer

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