On Mon, Aug 26, 2013 at 10:08:43AM -0400, Jason Cooper wrote:
> On Fri, Aug 23, 2013 at 07:12:20PM -0300, Ezequiel Garcia wrote:
> > Change the 'reg' property meaning, by defining two required cells.
> > It's important to note this commit breaks DT-compatibility for this
> > device.
> >
> > Cc: devicetree@xxxxxxxxxxxxxxx
> > Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> > ---
> > Documentation/devicetree/bindings/watchdog/orion-wdt.txt | 7 +++++--
> > 1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/watchdog/orion-wdt.txt b/Documentation/devicetree/bindings/watchdog/orion-wdt.txt
> > index 5dc8d30..a74c9c8 100644
> > --- a/Documentation/devicetree/bindings/watchdog/orion-wdt.txt
> > +++ b/Documentation/devicetree/bindings/watchdog/orion-wdt.txt
> > @@ -3,7 +3,9 @@
> > Required Properties:
> >
> > - Compatibility : "marvell,orion-wdt"
> > -- reg : Address of the timer registers
> > +- reg : Two cells are required:
> > + First cell contains the global timer control register.
> > + Second cell contains the watchdog counter register.
> >
> > Optional properties:
> >
> > @@ -13,7 +15,8 @@ Example:
> >
> > wdt@20300 {
> > compatible = "marvell,orion-wdt";
> > - reg = <0x20300 0x28>;
> > + reg = <0x20300 0x4
>
>
> > + 0x20324 0x4>;
>
> Is there a reason we're going this route over adding a new compatible
> string?
Well, it seemed to me that this register splitting was more device-treeish:
it prevents you from fixing your driver, adding a new compatible-string,
and rebuilding a kernel each time a new SoC appears with a different offset
between registers.
Instead, and trying to follow the DT-preachers, we would just change the
"reg" values and -bang!- have forward-compatibility :-)
That said...
> iow, why can't we keep this knowledge in the driver and have a
> "marvell,armada-wdt" or similar compat string that the orion-wdt driver
> also serves?
>
... we still need new compatible strings for armada-xp-wdt and
armada-370-wdt, for they have differences between each other
and with the orion-wdt:
* The clock input is obtained in a different way in each case
* The watchdog enable bit inside the timer control register
is at a different location.
So, thinking about this again, perhaps we should simply let alone the
"reg" property and add the watchdog counter offset as yet another field
in the compatible-data?
What do you think?
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
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