linux-kernel - Re: regmap: mmio: regression in pre-v4.6-rc1

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Message-ID: <20160323103415.GG2566@sirena.org.uk>
Date:	Wed, 23 Mar 2016 10:34:15 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Alexander Stein <alexander.stein@...tec-electronic.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: regmap: mmio: regression in pre-v4.6-rc1

On Wed, Mar 23, 2016 at 09:48:42AM +0100, Alexander Stein wrote:

Please fix your mail client to word wrap within paragraphs at something
substantially less than 80 columns.  Doing this makes your messages much
easier to read and reply to.

> I'm currently trying to get PCIe working on LS1021A (little-endian
> ARM). For link-detection I need access to a syscon perpheral (SCFG)
> which is attched to CPU as big-endian.

Are you *sure* that this is actually big endian?  Are you basing this on
documentation or on what happened to work for you in the past.

> Based on current linus's master (a24e3d414e59ac765, "Merge branch
> 'akpm' (patches from Andrew)") I noticed the access is actually done
> as little-endian.  I could track it down to commit 922a9f936e40001f
> ("regmap: mmio: Convert to regmap_bus and fix accessor usage").
> Reverting it, the access is fine now and I get my PCIe link.

Have you tried tracing through the code to see what ends up happening to
the I/O?  It should come out using your architecture's big endian
accessors.

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