Re: [RFC 4/5] RTC: rtc-at91sam9: add device-tree support

[Johan Hovold <jhovold@gmail.com>]

On Mon, Apr 08, 2013 at 01:11:13PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 12:38 Mon 08 Apr     , Johan Hovold wrote:
> > On Mon, Apr 08, 2013 at 11:57:06AM +0200, Nicolas Ferre wrote:
> > > On 04/08/2013 11:00 AM, Johan Hovold :
> > > > On Mon, Apr 08, 2013 at 09:38:07AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > >> On 17:12 Sun 07 Apr     , Johan Hovold wrote:

[...]

> > > >>> +rtt@fffffd20 {
> > > >>> +		compatible = "atmel,at91sam9g45-rtt", "atmel,at91sam9260-rtt";
> > > 
> > > No, there is no visible difference between the sam9g45 RTT and the
> > > sam9260 one. So the most precise compatibility string is still sam9260.
> > > If one day we feel the need for a advanced feature that exists on a more
> > > recent SoC, we have the possibility to add it at that time...
> > 
> > Yes, this should be just "atmel,at91sam9260-rtt" to follow the current
> > practise in AT91. However, as I mentioned in an earlier mail one could
> > interpret
> > 
> > 	"The first string in the list specifies the exact device that
> > 	the node represents in the form "<manufacturer>,<model>". The
> > 	following strings represent other devices that the device is
> > 	compatible with.
> > 
> > 	For example, the Freescale MPC8349 System on Chip (SoC) has a
> > 	serial device which implements the National Semiconductor
> > 	ns16550 register interface. The compatible property for the
> > 	MPC8349 serial device should therefore be: compatible =
> > 	"fsl,mpc8349-uart", "ns16550". In this case, fsl,mpc8349-uart
> > 	specifies the exact device, and ns16550 states that it is
> > 	register-level compatible with a National Semiconductor 16550
> > 	UART."
> > 
> > 	http://www.devicetree.org/Device_Tree_Usage#Understanding_the_compatible_Property
> > 
> > to mean that the compatible property should always be exact SoC-IP
> > followed by the first (most generic) compatible one.
>
> here you describe compatible IP not drivers implementation

I'm referring to the IP and not drivers.

> they are both usuart IP that are compatible at IP level.

Fair enough, I see how this can be considered to be in accordance with
the above quotation.

Johan