Re: [PATCH v5 2/5] dt-bindings: net: wireless: brcm4329-fmac: add clock description for AP6275P
From: Arend Van Spriel <arend.vanspriel@broadcom.com>
Date: 2024-07-30 11:17:07
Also in:
linux-arm-kernel, linux-devicetree, linux-rockchip, linux-wireless, lkml
On July 30, 2024 12:18:20 PM Krzysztof Kozlowski [off-list ref] wrote:
On 30/07/2024 11:52, Arend Van Spriel wrote:quoted
On July 30, 2024 11:01:43 AM Krzysztof Kozlowski [off-list ref] wrote:quoted
On 30/07/2024 08:37, Arend Van Spriel wrote:quoted
+ Linus W On July 30, 2024 5:31:15 AM Jacobe Zang [off-list ref] wrote:quoted
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 <redacted> --- .../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?Yes, it is handled correctly. That's a basic use-case, handled by CCF since some years (~12?). Anyway, whatever OS is doing (or not doing) with the clocks is independent of the bindings here. The question is
Agree. Probably the bindings would not be the place to document this if it would be an issue.
about hardware - does this node, which represents PCI interface of the chip, has/uses the clocks.
The schematics I found for the wifi module and the khadas edge platform show these are indeed wired to the chip. Regards, Arend
Best regards, Krzysztof