Messages in this thread | | | Date | Fri, 15 Dec 2023 19:42:04 +0800 | Subject | Re: [PATCH v2 5/5] dt-bindings: net: ipq4019-mdio: Document ipq5332 platform | From | Jie Luo <> |
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On 12/15/2023 6:53 PM, Krzysztof Kozlowski wrote: > On 15/12/2023 11:40, Jie Luo wrote: >> >> >> On 12/15/2023 6:37 PM, Krzysztof Kozlowski wrote: >>> On 15/12/2023 11:33, Jie Luo wrote: >>>>>>>>>>>> + cmn-reference-clock: >>>>>>>>>>>> + oneOf: >>>>>>>>>>>> + - items: >>>>>>>>>>>> + - enum: >>>>>>>>>>>> + - 0 # CMN PLL reference internal 48MHZ >>>>>>>>>>>> + - 1 # CMN PLL reference external 25MHZ >>>>>>>>>>>> + - 2 # CMN PLL reference external 31250KHZ >>>>>>>>>>>> + - 3 # CMN PLL reference external 40MHZ >>>>>>>>>>>> + - 4 # CMN PLL reference external 48MHZ >>>>>>>>>>>> + - 5 # CMN PLL reference external 50MHZ >>>>>>>>>>>> + - 6 # CMN PLL reference internal 96MHZ >>>>>>>>>>> >>>>>>>>>>> Why is this not represented by an element of the clocks property? >>>>>>>>>> >>>>>>>>>> This property is for the reference clock source selection of CMN PLL, >>>>>>>>>> CMN PLL generates the different clock rates for the different Ethernet >>>>>>>>>> blocks, this CMN PLL configuration is not located in the GCC, so the >>>>>>>>>> clock framework can't be used, which is the general hardware register >>>>>>>>>> instead of RCG register for GCC. >>>>>>>>> >>>>>>>>> I don't see how the clock being provided by the "GCC" (whatever that is) >>>>>>>>> or by some other clock controller or fixed clock makes a difference. >>>>>>>>> Why can't the other clock provider be represented in the devicetree? >>>>>>>>> >>>>>>>> >>>>>>>> cmn-reference-clock is for selecting the reference clock source for the >>>>>>>> whole Ethernet block, which is just the standalone configure register. >>>>>>> >>>>>>> Sure, you are aware though that all clocks are just configure registers? >>>>>>> >>>>>>> Which clocks are these mentioned in the property? From where do they come? >>>>>>> >>>>>>> Anyway, property is in existing form is not correct - this is not a >>>>>>> generic property. >>>>>>> >>>>>> >>>>>> This property cmn-reference-clock is just the hardware register >>>>>> configuration, since the different IPQ platform needs to select >>>>>> the different reference clock source for the CMN PLL block that >>>>>> provides the various clock outputs to the all kinds of Ethernet >>>>>> devices, which is not from GCC provider. >>>>> >>>>> AGAIN: where do the clocks come from? Which device generates them? >>>> >>>> Oh, OK, the reference clock is from wifi that provides 48MHZ to >>>> Ethernet block. >>> >>> Then WiFi should be providing you the clock and this device should be >>> clock consumer, right? >> >> Yes, wifi provides 48MHz clock to CMM PLL block, there is no GCC >> for this 48MHZ clock output, it is the hardware PIN connection. > > All clocks are some hardware pin connections. > > Best regards, > Krzysztof >
Yes, all reference clocks here are from hardware pin connection.
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