On 2024-07-15 19:46, Heiko Stübner wrote:
Am Montag, 15. Juli 2024, 17:15:45 CEST schrieb Dragan Simic:
On 2024-07-15 13:02, Heiko Stuebner wrote:
> In contrast to fixed clocks that are described as ungateable, boards
> sometimes use additional oscillators for things like PCIe reference
> clocks, that need actual supplies to get enabled and enable-gpios to be
> toggled for them to work.
>
> This adds a binding for such oscillators that are not configurable
> themself, but need to handle supplies for them to work.
>
> In schematics they often can be seen as
>
> ----------------
> Enable - | 100MHz,3.3V, | - VDD
> | 3225 |
> GND - | | - OUT
> ----------------
>
> or similar. The enable pin might be separate but can also just be tied
> to the vdd supply, hence it is optional in the binding.
>
> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> ---
> .../bindings/clock/voltage-oscillator.yaml | 49 +++++++++++++++++++
> 1 file changed, 49 insertions(+)
> create mode 100644
> Documentation/devicetree/bindings/clock/voltage-oscillator.yaml
>
> diff --git
> a/Documentation/devicetree/bindings/clock/voltage-oscillator.yaml
> b/Documentation/devicetree/bindings/clock/voltage-oscillator.yaml
> new file mode 100644
> index 0000000000000..8bff6b0fd582e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/voltage-oscillator.yaml
> @@ -0,0 +1,49 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/clock/voltage-oscillator.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Voltage controlled oscillator
Frankly, I find the "voltage-oscillator" and "voltage controlled
oscillator" names awkward. In general, "clock" is used throughout
the entire kernel, when it comes to naming files and defining
"compatible" strings. Thus, I'd suggest that "clock" is used here
instead of "oscillator", because it's consistent and shorter.
How about using "gated-clock" for the "compatible" string, and
"Simple gated clock generator" instead of "voltage controlled
oscillator"? Besides sounding awkward, "voltage controlled
oscillator" may suggest that the clock generator can be adjusted
or programmed somehow by applying the voltage, while it can only
be enabled or disabled that way, which is by definition clock
gating. Thus, "gated-clock" and "Simple gated clock generator"
would fit very well.
The naming came from Stephen - one of the clock maintainers ;-)
See discussion in v1. Who also described these things as
"voltage-controlled-oscillators".
And from that discussion I also got the impression we should aim for
more specific naming - especially when talking about dt-bindings, for
this
"usage in the Linux kernel" actually isn't a suitable metric and
"gated-clock" is probably way too generic I think.
I see, thanks for the clarification. Though, the generic nature of
"gated-clock" as the name may actually make this driver a bit more
future-proof, by allowing some other features to be added to it at
some point in the future, avoiding that way the need for yet another
kernel driver.
Though I'm not attached to any specific naming, so we'll simply
wait for the clock- and dt-maintainers to weigh in ;-)
