On Wed, 13 Jul 2011 19:52:12 +0400
Anton Vorontsov <[email protected]> wrote:
> On Wed, Jul 06, 2011 at 03:05:18PM -0600, Grant Likely wrote:
> > On Thu, Jul 07, 2011 at 12:47:50AM +0800, Shawn Guo wrote:
> > > +- cd-gpios : Specify GPIOs for card detection
> > > +- wp-gpios : Specify GPIOs for write protection
> [...]
> > > + cd-gpios = <&gpio0 6 0>; /* GPIO1_6 */
> > > + wp-gpios = <&gpio0 5 0>; /* GPIO1_5 */
>
> Is there any particular reason why we started using named GPIOs
> in the device tree? To me, that's quite drastic change... should
> we start using named regs and interrupts as well? Personally, I
> don't think that the idea is great, as now you don't know where
> to expect memory resources, interrupt resources and, eventually
> GPIO resources.
Just check the binding, and you'll know. :-)
It makes it easier to deal with cases where some resources are optional,
especially when dealing with a binding for a family of devices that grows
over time, and helps avoid resources being mismatched since order no longer
matters.
> Just a few disadvantages off the top of my head:
>
> - You can't statically validate your device tree for correctness.
> Today dtc checks #{address,size}-cells sanity for 'regs' and
> 'ranges';
The vast majority of stuff in the device tree already cannot be checked in
this manner, without adding binding knowledge to dtc.
Perhaps it could check things that end in "-gpios", "-regs", etc., if we
avoid adding new properties that match those patterns that aren't what they
appear to be, and let dtc know about any existing cases.
> - You can't automatically convert named resources into 'struct
> resource *', as we do for platform devices now;
So add named resource support to platform devices. :-)
-Scott
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