Re: [PATCH v3 1/2] dt-bindings: Add GPIO-locked fixed clock

[Vyacheslav Yurkov]

Hi Brian

On 16.06.2026 00:01, Brian Masney wrote:
> Hi Vyacheslav,
>
> On Wed, Jun 03, 2026 at 11:16:42AM +0000, Vyacheslav Yurkov via B4 Relay wrote:
> > From: Vyacheslav Yurkov <V.Yurkov.EXT@xxxxxxxxxx>
> >
> > Some hardware designs provide fixed-frequency clocks generated outside
> > software control, such as by FPGA-resident PLLs. While the clock rate is
> > fixed, a separate GPIO signal indicates whether the clock source is
> > locked and producing a valid output.
> >
> > Describe a GPIO-locked fixed clock provider that exposes a fixed-rate
> > clock whose availability depends on one or more GPIO lock-status
> > signals.
> >
> > Signed-off-by: Vyacheslav Yurkov <uvv.mail@xxxxxxxxx>
> > Signed-off-by: Vyacheslav Yurkov <V.Yurkov.EXT@xxxxxxxxxx>
> > ---
> >   .../bindings/clock/gpio-locked-fixed-clock.yaml    | 70 ++++++++++++++++++++++
> >   1 file changed, 70 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/clock/gpio-locked-fixed-clock.yaml b/Documentation/devicetree/bindings/clock/gpio-locked-fixed-clock.yaml
> > new file mode 100644
> > index 000000000000..9106b800b673
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/gpio-locked-fixed-clock.yaml
> > @@ -0,0 +1,70 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/clock/gpio-locked-fixed-clock.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: GPIO Locked Fixed Clock
> > +
> > +maintainers:
> > +  - Vyacheslav Yurkov <V.Yurkov.EXT@xxxxxxxxxx>
> > +
> > +description: |
> > +  Provides a clock output whose availability depends on a set of
> > +  prerequisite conditions. These conditions include the presence of
> > +  one or more parent clocks and the asserted state of one or more
> > +  GPIO lock indicators. An example of such clocks is FPGA clock that
> > +  are outside CPU control, with the lock status exposed through GPIO
> > +  signal.
> > +
> > +  The output clock is considered available only when all configured
> > +  prerequisites are satisfied.
>
> I'm stepping outside my usual review of just the clk drivers. Krzysztof
> in v1 and v2 asked for more detailed hardware explanation. This feels to
> me like this is a policy that says to not use these clocks until the
> GPIO says they are ready. My gut feeling is that details like this
> should live in a clk driver instead of a dt-binding.
>
> Alternatively, if this is generic enough, then could
> Documentation/devicetree/bindings/clock/gated-fixed-clock.yaml be
> extended?
>
> Brian
Does it mean I should drop driver description from the DT schema?

So you are implying that gated-fixed-clock.yaml can be extended with 
another compatibility string? When another compatibility string is used, 
then some other bindings are expected by the driver, not what is used by 
gated-fixed-clock driver. Is that a common pattern among dt-bindings to 
share the bindings between different compatibility strings?

Slava