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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 29 Oct 2014 09:30:36 -0500
From:	atull <atull@...nsource.altera.com>
To:	Steffen Trumtrar <s.trumtrar@...gutronix.de>
CC:	Mark Brown <broonie@...nel.org>, <jgunthorpe@...idianresearch.com>,
	<hpa@...or.com>, <monstr@...str.eu>, <michal.simek@...inx.com>,
	<rdunlap@...radead.org>, <gregkh@...uxfoundation.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<pantelis.antoniou@...sulko.com>, <robh+dt@...nel.org>,
	<grant.likely@...aro.org>, <iws@...o.caltech.edu>,
	<linux-doc@...r.kernel.org>, <pavel@...x.de>,
	<philip@...ister.org>, <rubini@...dd.com>, <jason@...edaemon.net>,
	<kyle.teske@...com>, <nico@...aro.org>, <balbi@...com>,
	<m.chehab@...sung.com>, <davidb@...eaurora.org>, <rob@...dley.net>,
	<davem@...emloft.net>, <cesarb@...arb.net>,
	<sameo@...ux.intel.com>, <akpm@...ux-foundation.org>,
	<linus.walleij@...aro.org>, <mgerlach@...nsource.altera.com>,
	<delicious.quinoa@...il.com>, <dinguyen@...nsource.altera.com>,
	<yvanderv@...nsource.altera.com>
Subject: Re: [PATCH v2 2/3] ARM: dts: socfpga: fpga bridges bindings docs

On Wed, 29 Oct 2014, Steffen Trumtrar wrote:

> 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.

Yes, you can read and it will be all 0s.  So read-modify-write is not
something you would want to do for instance.

Alan

> So, I shot myself in the knee with specifying that register as write-only
> in my driver.
> 
> Thanks,
> Steffen
> 
> -- 
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/