On 10/09/2014 17:52, Johan Hovold :

On Wed, Sep 10, 2014 at 05:31:14PM +0200, Boris BREZILLON wrote:

quoted

On Wed, 10 Sep 2014 17:07:02 +0200
Johan Hovold [off-list ref] wrote:

quoted

quoted

Yes, this essentially what I suggested in the thread (and my last reply)
and relying on syscon rather than a custom driver seems like a good
idea. It would allow early access to the registers too with the recently
proposed changes. It would not guarantee any kind of exclusivity,
though, but I guess that's tolerable?

Yep, that's one of the concern I had with the syscon/regmap
approach :-(, but I guess I'll give this solution a try and post a new
version of this series ;-).

Perhaps we should see what Nicolas and Jean-Christophe says before
rushing into anything (again). ;)

I said and say it again: keep it simple: if gpbr 0 is used by bootloader
to pass information about the boot media, use gpbr 1, without protection
without anything fancy, please.

atmel,at91-rtt-as-rtc-gpbr = <1>;
is good for me.

We can decide to keep the DT binding as "unstable" and see what happen
in one year from now (I suspect nothing will happen). The result is that
we will have a simple update of this driver without new API or new
sub-system to learn and maintain.

So, all in all, I would just take what Johan or Boris did, and go with
this, now!

I remember J-C considered loosing track of what was using a particular
backup register to be a regression. But I guess you can't have it both
ways (e.g. if you also want the early access soon provided by syscon).

I'll refresh my rtt and gmbr-node patches meanwhile, as they should be
needed in some form at least.

quoted

Can we just leave the rtt as an rtc problem on the side for now and bind
it to the rtc-at91sam9 driver.

If we ever decide to add a new driver using the RTT for another purpose
we will still be able to reference the RTT block like this (and keep
the existing rtt node definition):

rtt-based-rtc {
	compatible = "atmel,rtt-rtc";
	atmel,rtt = <&rtt>;
	atmel,time-reg = <&gpbr 0x0>;
}

But why not do this from the start?

quoted

rtt-based-xdev {
	compatible = "atmel,rtt-xdev";
	atmel,rtt = <&rtt>;
	/*...*/
}

Johan

-- 
Nicolas Ferre