On 27/08/2013 05:54, Stephen Warren wrote:
On 08/26/2013 12:45 PM, boris brezillon wrote:
Hello Jean-Christophe,
Le 26/08/2013 19:53, Jean-Christophe PLAGNIOL-VILLARD a écrit :
On 23:37 Sat 24 Aug , Boris BREZILLON wrote:
Add support for generic pin configuration to pinctrl-at91 driver.
...
a/Documentation/devicetree/bindings/pinctrl/atmel,at91-pinctrl.txt
...
configures various pad settings
such as pull-up, multi drive, etc.
Required properties for iomux controller:
-- compatible: "atmel,at91rm9200-pinctrl"
+- compatible: "atmel,at91rm9200-pinctrl" or "atmel,at91sam9x5-pinctrl".
+ Add "generic-pinconf" to the compatible string list to use the
generic pin
...
+pinctrl@fffff400 {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+ compatible = "atmel,at91rm9200-pinctrl", "generic-pinconf",
"simple-bus";
nack your break the backword compatibility
if we use a old kernel with this new dt nothing will work
as the old kernel will never known the the "generic-pinconf" means
anything
Your're right, I didn't think of this case (old kernel with new dt).
Well, just to be clear: If a new DT uses a new compatible value of any
kind, be it adding "generic-pinconf" or switching to "foo-yyy" rather
than "foo-yyy", it won't be compatible... That somewhat implies that you
can't ever replace an old binding with something new.
That's absolutely right, however the behaviour won't be the same in both
cases.
1) If your (new) dt defines its pinctrl using the "foo-pinconf"
compatible string and
your (old) kernel does not support it, the pinctrl will never probe
the pinctrl definitions.
Moreover, if you want to define both old ("foo-pinctrl") and new
("foo-pinconf") pinctrl
definitions in your dt in order to support several kernel versions,
nothing prevents you
from doing it.
2) In the other hand, if you use an additional "generic-pinconf"
compatible string to signify
wether or not the pinctrl definition use the generic pinconf dt
binding, the (old) kernel
will probe the pinctrl definitions, ignore the "generic-pinconf"
string, and fail when parsing
the pinctrl configuration nodes (which are invalid pinctrl function
nodes in the current dt binding).
We have the same problem when using the 'atmel,generic-pinconf'
property inside a pinctrl node:
old kernels won't take this property into account.
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