Re: [PATCH v5 2/5] dt-bindings: net: wireless: brcm4329-fmac: add clock description for AP6275P

Arend Van Spriel
2024-07-30T09:53:03Z

On July 30, 2024 11:01:43 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:

> On 30/07/2024 08:37, Arend Van Spriel wrote:
>> + Linus W
>>
>> On July 30, 2024 5:31:15 AM Jacobe Zang <jacobe.zang@wesion.com> wrote:
>>
>>> Not only AP6275P Wi-Fi device but also all Broadcom wireless devices allow
>>> external low power clock input. In DTS the clock as an optional choice in
>>> the absence of an internal clock.
>>>
>>> Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
>>> Signed-off-by: Jacobe Zang <jacobe.zang@wesion.com>
>>> ---
>>> .../bindings/net/wireless/brcm,bcm4329-fmac.yaml | 8 ++++++++
>>> 1 file changed, 8 insertions(+)
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/net/wireless/brcm,bcm4329-fmac.yaml
>>> b/Documentation/devicetree/bindings/net/wireless/brcm,bcm4329-fmac.yaml
>>> index 2c2093c77ec9a..a3607d55ef367 100644
>>> --- a/Documentation/devicetree/bindings/net/wireless/brcm,bcm4329-fmac.yaml
>>> +++ b/Documentation/devicetree/bindings/net/wireless/brcm,bcm4329-fmac.yaml
>>> @@ -122,6 +122,14 @@ properties:
>>> NVRAM. This would normally be filled in by the bootloader from platform
>>> configuration data.
>>>
>>> + clocks:
>>> + items:
>>> + - description: External Low Power Clock input (32.768KHz)
>>> +
>>> + clock-names:
>>> + items:
>>> + - const: lpo
>>> +
>>
>> We still have an issue that this clock input is also present in the
>> bindings specification broadcom-bluetooth.yaml (not in bluetooth
>> subfolder). This clock is actually a chip resource. What happens if both
>> are defined and both wifi and bt drivers try to enable this clock? Can this
>> be expressed in yaml or can we only put a textual warning in the property
>> descriptions?
>
> Just like all clocks, what would happen? It will be enabled.

Oh, wow! Cool stuff. But seriously is it not a problem to have two entities
controlling one and the same clock? Is this use-case taken into account by
the clock framework?

Regards,
Arend