From: Arnd Bergmann <arnd@arndb.de>
To: "Jean-Christophe PLAGNIOL-VILLARD" <plagnioj@jcrosoft.com>
Subject: Re: [PATCH v2 12/19] ARM: at91/rtc-at91sam9: each SoC can select the RTT device to use
Date: Wed, 22 Feb 2012 16:47:23 +0000
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Cc: Nicolas Ferre <nicolas.ferre@atmel.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        rmallon@gmail.com, linux@arm.linux.org.uk
References: <1329903585-30738-1-git-send-email-nicolas.ferre@atmel.com> <201202221450.04390.arnd@arndb.de> <20120222162442.GD9407@game.jcrosoft.org>
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On Wednesday 22 February 2012, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 14:50 Wed 22 Feb     , Arnd Bergmann wrote:
> > On Wednesday 22 February 2012, Nicolas Ferre wrote:
> > > From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
> > > 
> > > For the RTT as RTC driver rtc-at91sam9, the platform_device structure
> > > is filled during SoC initialization. This will allow to convert this
> > > RTC driver as a standard platform driver.
> > 
> > Can you make this more elaborate? I don't see from this or the code why
> > you don't just always register the RTT as "rtc-at91sam9". There seems to
> > be no driver for the "at91_rtt" in tree, so I don't know if there is
> > an out of tree driver binding to it.
> > 
> > Would it be possible to remove the compile time #if and the resetting
> > of the device name if both drivers bind to the rtc name and the other
> > rtt driver binds to both names?
> because I see a quite some people use the rtt for something else
> 
> so I don't want to change on existing kernel

But if you change the rtc driver to always bind to the existing
"at91_rtt" platform_device and fail the probe() function for the
case that you are on at91sam9263 probing the non-RTC device,
you should get the exact same result without any extra code
in the per-soc files.

I guess it also makes sense to specify a device tree property
that lets you detect whether the RTT is used as RTC or something
else.

	Arnd
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