On 23/08/2024 11:44, Manivannan Sadhasivam wrote: > On Fri, Aug 23, 2024 at 11:01:37AM +0200, Krzysztof Kozlowski wrote: >> On 22/08/2024 16:16, Manivannan Sadhasivam wrote: >>> On Mon, Aug 05, 2024 at 04:43:47PM +0200, Krzysztof Kozlowski wrote: >>>> On 05/08/2024 07:57, Krishna Chaitanya Chundru wrote: >>>>>> >>>>> Hi Krzysztof, >>>>> >>>>> QPS615 has a 3 downstream ports and 1 upstream port as described below >>>>> diagram. >>>>> For this entire switch there are some supplies which we described in the >>>>> dt-binding (vdd18-supply, vdd09-supply etc) and one GPIO which controls >>>>> reset of the switch (reset-gpio). The switch hardware can configure the >>>>> individual ports DSP0, DSP1, DSP2, upstream port and also one integrated >>>>> ethernet endpoint which is connected to DSP2(I didn't mentioned in the >>>>> diagram) through I2C. >>>>> >>>>> The properties other than supplies,i2c client, reset gpio which >>>>> are added will be applicable for all the ports. >>>>> _______________________________________________________________ >>>>> | |i2c| QPS615 |Supplies||Resx gpio | >>>>> | |___| _________________ |________||__________| >>>>> | ________________| Upstream port |_____________ | >>>>> | | |_______________| | | >>>>> | | | | | >>>>> | | | | | >>>>> | ____|_____ ____|_____ ___|____ | >>>>> | |DSP 0 | | DSP 1 | | DSP 2| | >>>>> | |________| |________| |______| | >>>>> |_____________________________________________________________| >>>>> >>>> >>>> I don't get why then properties should apply to main device node. >>>> >>> >>> The problem here is, we cannot differentiate between main device node and the >>> upstream node. Typically the differentiation is not needed because no one cared >>> about configuring the upstream port. But this PCIe switch is special (as like >>> most of the Qcom peripherals). >>> >>> I agree that if we don't differentiate then it also implies that all main node >>> properties are applicable to upstream port and vice versa. But AFAIK, upstream >>> port is often considered as the _device_ itself as it shares the same bus >>> number. >> >> Well, above diagram shows supplies being part of the entire device, not >> each port. That's confusing. Based on diagram, downstream ports do not >> have any supplies... and what exactly do they supply? Let's look at >> vdd18 and vdd09 which sound main supplies of the entire device. In >> context of port: what exactly do they power? Which part of the port? >> > > The supplies for the downstream ports are derived from the switch power supply > only. There is no way we can describe them as the port suppliers are internal to > the device. IIUC, this means supplies are not valid for downstream ports, so it is a proof that binding is not correct. I don't get why we keep poking this and get to the same conclusions I had 3 weeks ago. Basically the binding is saying that downstream ports are identical to the device. Including the aspect of having more downstream ports (so device -> downstream ports -> downstream ports -> downstream ports ... infinite). To remind that was my conclusion: "Downstream port is not the same as device. Why downstream port has the same supplies? To which pins are they connected?" Best regards, Krzysztof
