Re: [PATCH v3 1/2] dt-bindings: pwm: Add Xilinx AXI Timer

On Thu, May 13, 2021 at 10:28 AM Sean Anderson [off-list ref] wrote:

On 5/13/21 10:33 AM, Sean Anderson wrote:
 >
 >
 > On 5/12/21 10:16 PM, Rob Herring wrote:
 >  > On Tue, May 11, 2021 at 03:12:37PM -0400, Sean Anderson wrote:
 >  >> This adds a binding for the Xilinx LogiCORE IP AXI Timer. This device is
 >  >> a "soft" block, so it has many parameters which would not be
 >  >> configurable in most hardware. This binding is usually automatically
 >  >> generated by Xilinx's tools, so the names and values of some properties
 >  >> must be kept as they are. Replacement properties have been provided for
 >  >> new device trees.
 >  >
 >  > Because you have some tool generating properties is not a reason we have
 >  > to accept them upstream.
 >
 > These properties are already in arch/microblaze/boot/dts/system.dts and
 > in the devicetree supplied to Linux by qemu. Removing these properties
 > will break existing setups, which I would like to avoid.

Already in use in upstream dts files is different than just
'automatically generated' by vendor tools.

 >
 >  > 'deprecated' is for what *we* have deprecated.
 >
 > Ok. I will remove that then.
 >
 >  >
 >  > In this case, I don't really see the point in defining new properties
 >  > just to have bool.
 >
 > I don't either, but it was requested, by Michal...

Err, your comment on the original bindings was

 > Can't all these be boolean?

With no other context, yes that's what I would ask. Now you've given
me some context, between using the existing ones and 2 sets of
properties to maintain, I choose the former.

And Michal commented

 > I think in this case you should described what it is used by current
 > driver in Microblaze and these options are required. The rest are by
 > design optional.
 > If you want to change them to different value then current binding
 > should be deprecated and have any transition time with code alignment.

So that is what I tried to accomplish with this revision. I also tried
allowing something like

        xlnx,one-timer-only = <0>; /* two timers */
        xlnx,one-timer-only = <1>; /* one timer  */
        xlnx,one-timer-only; /* one timer */
        /* property absent means two timers */

but I was unable to figure out how to express this with json-schema. I
don't think it's the best design either...

json-schema would certainly let you, but generally we don't want
properties to have more than 1 type.

Rob