On 08/08/2024 14:01, Manivannan Sadhasivam wrote: > On Mon, Aug 05, 2024 at 07:18:04PM +0200, Krzysztof Kozlowski wrote: >> On 05/08/2024 19:07, Bjorn Andersson wrote: >>> On Mon, Aug 05, 2024 at 09:41:26AM +0530, Krishna Chaitanya Chundru wrote: >>>> On 8/4/2024 2:23 PM, Krzysztof Kozlowski wrote: >>>>> On 03/08/2024 05:22, Krishna chaitanya chundru wrote: >>>>>> diff --git a/Documentation/devicetree/bindings/pci/qcom,qps615.yaml b/Documentation/devicetree/bindings/pci/qcom,qps615.yaml >>> [..] >>>>>> + qps615,axi-clk-freq-hz: >>>>>> + description: >>>>>> + AXI clock which internal bus of the switch. >>>>> >>>>> No need, use CCF. >>>>> >>>> ack >>> >>> This is a clock that's internal to the QPS615, so there's no clock >>> controller involved and hence I don't think CCF is applicable. >> >> AXI does not sound that internal. > > Well, AXI is applicable to whatever entity that implements it. We mostly seen it > in ARM SoCs (host), but in this case the PCIe switch also has a microcontroller > /processor of some sort, so AXI is indeed relevant for it. The naming actually > comes from the switch's i2c register name that is being configured in the driver > based on this property value. > >> DT rarely needs to specify internal >> clock rates. What if you want to define rates for 20 clocks? Even >> clock-frequency is deprecated, so why this would be allowed? >> bus-frequency is allowed for buses, but that's not the case here, I guess? >> > > This clock frequency is for the switch's internal AXI bus that runs at default > 200MHz. And this property is used to specify a frequency that is configured over > the i2c interface so that the switch's AXI bus can operate in a low frequency > there by reducing the power consumption of the switch. > > It is not strictly needed for the switch operation, but for power optimization. > So this property can also be dropped for the initial submission and added later > if you prefer. So if the clock rate can change, why this is static in DTB? Or why this is configurable per-board? There is a reason why clock-frequency property is not welcomed and you are re-implementing it. Best regards, Krzysztof
