Messages in this thread | | | Date | Fri, 15 Dec 2023 18:40:54 +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 6:37 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. > > > > Best regards, > Krzysztof >
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