Re: [PATCH 1/5] dt-bindings: spi: zynqmp-qspi: Add reset

Sean Anderson
2025-01-27T18:00:25Z

On 1/27/25 12:57, Rob Herring wrote:
> On Thu, Jan 23, 2025 at 05:57:41PM -0500, Sean Anderson wrote:
>> On 1/23/25 17:45, Rob Herring wrote:
>> > On Fri, Jan 17, 2025 at 11:12:15AM -0500, Sean Anderson wrote:
>> >> On 1/17/25 02:14, Michal Simek wrote:
>> >> >
>> >> >
>> >> > On 1/16/25 23:55, Sean Anderson wrote:
>> >> >> Add a reset to help recover from cancelled operations.
>> >> >>
>> >> >> Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
>> >> >> ---
>> >> >>
>> >> >> Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml | 6 ++++++
>> >> >> 1 file changed, 6 insertions(+)
>> >> >>
>> >> >> diff --git a/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml b/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml
>> >> >> index 04d4d3b4916d..901e15fcce2d 100644
>> >> >> --- a/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml
>> >> >> +++ b/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml
>> >> >> @@ -36,12 +36,16 @@ properties:
>> >> >> power-domains:
>> >> >> maxItems: 1
>> >> >> + resets:
>> >> >> + maxItems: 1
>> >> >> +
>> >> >> required:
>> >> >> - compatible
>> >> >> - reg
>> >> >> - interrupts
>> >> >> - clock-names
>> >> >> - clocks
>> >> >> + - resets
>> >> >
>> >> > In 2/5 you are calling devm_reset_control_get_optional_exclusive() that's why I expect reset is not really required property.
>> >>
>> >> It's optional for the driver for backwards compatibility. But for the
>> >> devicetree we make it mandatory since it should be included in all new
>> >> devicetrees.
>> >
>> > Generally, we discourage new required properties as that's an ABI
>> > change. The exception is really when optional was a mistake. That's
>> > arguably the case here if the h/w always has a reset.
>>
>> This device has a reset on ZynqMP and Versal.
>>
>> The driver still considers this property optional, so it's not an ABI break.
>> But I made it required in the schema to help out the folks at AMD when they
>> get around to upstreaming the Versal devicetree :)
>
> Not 'the driver', but 'a driver'. You can't say what *all* drivers do.
> If I write a new driver and read the schema, then I can say 'resets is
> required so I'll make it required in my new driver'. But then my new
> driver doesn't work with an older DT that didn't have resets which was
> valid at the time.

OK, I'll add a description to this effect. The humans can read that, and
the machines won't care.

--Sean