Am Freitag, 3. Januar 2014, 10:23:50 schrieb Dmitry Torokhov:
> On Fri, Jan 03, 2014 at 06:36:05PM +0100, Maxime Ripard wrote:
> > On Thu, Jan 02, 2014 at 11:36:33PM +0100, Hans de Goede wrote:
> > > Hi,
> > >
> > > On 01/02/2014 09:20 PM, Maxime Ripard wrote:
> > > >On Thu, Jan 02, 2014 at 02:45:29PM +0100, Hans de Goede wrote:
> > > >>>Also, instead of inventing yet another vendor-specific property, why
> > > >>>not re-use> > >>>
> > > >>>a button binding similar to gpio-keys like:
> > > >>> lradc: lradc@01c22800 {
> > > >>>
> > > >>> compatible = "allwinner,sun4i-lradc-keys";
> > > >>> reg = <0x01c22800 0x100>;
> > > >>> interrupts = <31>;
> > > >>> allwinner,chan0-step = <200>;
> > > >>>
> > > >>> #address-cells = <1>;
> > > >>> #size-cells = <0>;
> > > >>>
> > > >>> button@0 {
> > > >>>
> > > >>> reg = <0>; /* your channel index from above */
> > > >>> linux,code = <115>; /* already used as dt-property */
> > > >>>
> > > >>> };
> > > >>>
> > > >>> button@1 {
> > > >>>
> > > >>> reg = <1>;
> > > >>> linux,code = <114>;
> > > >>>
> > > >>> };
> > > >>
> > > >>Ugh no. Having a vendor specific property which is KISS certainly
> > > >>beats this, both wrt ease of writing dts files as well as wrt the
> > > >>dts parsing code in the driver.
> > > >
> > > >I'd agree with Heiko here. This is pretty much the same construct
> > > >that's already in use in other input drivers, like gpio-keys.
> > >
> > > In the gpio case there is a 1 on 1 relation between a single hw
> > > entity (the gpio-pin) and a single keycode. Here there is 1 hw entity
> > > which maps to an array of key-codes, certainly using an array rather
> > > then a much more complicated construct is the correct data-structure
> > > to represent this.
> >
> > You can build an array in your driver out of this very easily, it's 10
> > lines in your probe. And you gain from this something that is more
> > generic, can be shared by other similar drivers and is consistent with
> > what is already in use.
>
> How will it be shared? Surely not code-wise, but basically in spirit
> only. It seems to me that the originally proposed binding is simple and
> concise and works well for the driver.
I don't think "binding [...] works well for the driver" is the correct
direction. From my understanding the binding should describe the hardware in
an os-agnostic way (so "linux,foo" properties should stay the exception) and
not the data structures used in the driver. The driver itself then implements
the binding to convert the binding-data into a structure it wants to use.
The sharing would, as you suggested, be in spirit and in the use of already
established dt-properties without introducing more non-standard ones.
Heiko
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