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    SubjectRe: [PATCH v3 1/3] dt-bindings: phy: qcom,qmp: Add PCIe qcom,refclk-always-on property
    On Thu, Dec 07, 2023 at 02:05:12PM +0100, Johan Hovold wrote:
    > On Thu, Dec 07, 2023 at 03:42:52PM +0530, Manivannan Sadhasivam wrote:
    > > On Thu, Dec 07, 2023 at 10:51:09AM +0100, Johan Hovold wrote:
    > > > On Wed, Dec 06, 2023 at 06:40:09PM +0530, Manivannan Sadhasivam wrote:
    > > >
    > > > > OK. How about, "qcom,broken-refclk"? This reflects the fact that the default
    > > > > refclk operation is broken on this platform, so the OS should be prepared for
    > > > > it (by keeping it always on).
    > > >
    > > > Shouldn't that be
    > > >
    > > > qcom,broken-clkreq
    > > >
    > > > since its the CLKREQ# signal used to request REFCLK that is broken, not
    > > > the REFCLK itself?
    > > >
    > >
    > > Darn... You are right. I got carried away by the initial property name. Thanks
    > > for spotting!
    >
    > Thinking some more on this after hitting send: It may still be wrong
    > with a 'broken-clkreq' property in the PHY instead of in the controller
    > (or endpoint).
    >
    > Could there not be other ways to handle a broken clkreq signal so that
    > this really should be a decision made by the OS, for example, to disable
    > L1 substates and clock PM?
    >

    One has to weigh the power consumption between keeping refclk always on and
    disabling L1SS. Chaitanya, can you measure power consumption in both cases?

    > Simply leaving the refclk always on in the PHY seems like a bit of a
    > hack and I'm not even sure that can be considered correct.
    >

    I wouldn't agree it is a hack, even though it may sound like one. The option to
    keep refclk always on in the PHY is precisely there for usecase like this.

    - Mani

    > Having a property that maps directly to that behaviour has rightly been
    > rejected, but it seems that simply renaming the flag but keeping it in
    > the PHY may still not be the right thing to do here.
    >
    > Johan

    --
    மணிவண்ணன் சதாசிவம்

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