Re: [PATCH v11 13/13] arm64: dts: qcom: sa8540-ride: Enable first port of tertiary usb controller

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On 9/14/23 17:45, Krishna Kurapati PSSNV wrote:


On 9/13/2023 5:40 PM, Konrad Dybcio wrote:
On 7.09.2023 05:36, Krishna Kurapati PSSNV wrote:


Is there any benefit to removing the other ports?

i.e. are ports 1-3 not parked properly by the dwc3 driver if
they're never connected to anything?

Hi Konrad,

  Whether or not the phy is connected to a port, the controller would modify the GUSB2PHYCFG/GUSB3PIPECTL registers. But if we don't specify only one phy and let phys from base DTSI take effect (4 HS / 2 SS), we would end up initializing and powering on phy's which are never connected to a port. To avoid that we need to specify only one phy for this platform.
And does that have any major effect on power use?

Do these PHYs not have some dormant/low power mode?

Hi Konrad,

 I believe there will be some minimal power use. IMO its best to keep only one phy enabled for this variant instead of giving all and initializing/powering-on all 4 of them.
Okay let's not waste power..

Konrad




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