linux-kernel - Re: [PATCH v2 2/3] ARM: dts: socfpga: fpga bridges bindings docs

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Message-ID: <20141029103103.GD10262@pengutronix.de>
Date:	Wed, 29 Oct 2014 11:31:03 +0100
From:	Steffen Trumtrar <s.trumtrar@...gutronix.de>
To:	Mark Brown <broonie@...nel.org>
Cc:	atull <atull@...nsource.altera.com>,
	jgunthorpe@...idianresearch.com, hpa@...or.com, monstr@...str.eu,
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Subject: Re: [PATCH v2 2/3] ARM: dts: socfpga: fpga bridges bindings docs

On Wed, Oct 29, 2014 at 10:16:32AM +0000, Mark Brown wrote:
> On Wed, Oct 29, 2014 at 08:57:01AM +0100, Steffen Trumtrar wrote:
> 
> > So, that shouldn't be a problem though, as I already cooked up a driver for
> > the L3 with all the ranges specified. The only thing I need to figure out
> > before I will post it, is how to nicely handle the WO remap register.
> > I think regmap might be able to handle this itself, but am not sure yet.
> 
> It's supposed to be able to, not sure if anyone really tests that or not
> though so it's possible bugs crept in.  Most write only registers can
> physically be read so actually come out as volatile rather than write
> only even if functionally there is no reason to read.

Ah, I think you might be actually right there. IIRC it IS possible to read
from that register, but you only get 0s.
So, I shot myself in the knee with specifying that register as write-only
in my driver.

Thanks,
Steffen

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