Re: [PATCH 1/2] dt-bindings: phy: qcom,sc8280xp-qmp-pcie-phy: Add vdda-refgen supply for Glymur

[Qiang Yu]

On Tue, Mar 03, 2026 at 12:14:29PM +0100, Konrad Dybcio wrote:
> On 3/2/26 11:21 AM, Qiang Yu wrote:
> > On Fri, Feb 13, 2026 at 07:47:36PM +0200, Dmitry Baryshkov wrote:
> >> On Wed, Feb 11, 2026 at 07:32:23PM -0800, Qiang Yu wrote:
> >>> On Mon, Feb 09, 2026 at 09:06:23AM +0100, Krzysztof Kozlowski wrote:
> >>>> On Sun, Feb 08, 2026 at 08:49:39PM -0800, Qiang Yu wrote:
> >>>>> The PCIe QMP PHYs on Glymur require stable reference voltage provided by
> >>>>> refgen. The refgen itself requires two separate power supplies:
> >>>>> vdda-refgen0p9 and vdda-refgen1p2.
> >>>>>
> >>>>> Since there is no dedicated driver for REFGEN, add vdda-refgen0p9-supply
> >>>>
> >>>> How does the driver matter for the bindings? If I add dedicated driver
> >>>> for refgen, then I change the bindings?
> >>>
> >>> Yeah, I know that dt-bindings should describe hardware, not software. But
> >>> what I meant to say is that the refgen is different from qref which is
> >>> controlled via TCSR registers and its LDOs are requested to vote in
> >>> tcsrcc driver. The refgen doesn't required register setting and it doesn't
> >>> have dedicated driver, so we vote its LDOs in phy driver. I will avoid
> >>> this statement in next version.
> >>
> >> I must admit, I could not find references to the refgen in any of Glymur
> >> PCIe-related HPGs.
> >>
> >>>
> >>>>
> >>>> There is qcom,sc8280xp-refgen-regulator so why there cannot be
> >>>> qcom,x1e-refgen-regulator?
> >>>
> >>> I think we can and it seems better because the refgen for pcie phy also
> >>> supplies reference voltage to other modules like usb. But I checked the
> >>> qcom-refgen-regulator.c, it contains some register settings and there is
> >>> no LDOs voting. I'm not sure what does those register do, maybe Konrad
> >>> can provide some backgroud.
> >>
> >> Those regs provide voting for refgen, because on those platforms DSI
> >> block doesn't have a hardware vote for refgen.
> > 
> > Hi Konrad, Dmitry
> > 
> > I tried to model the reference voltage as a fixed regulator but the fixed
> > regulator driver only supports a single vin-supply. However, the refgen
> > block requires two separate power supplies (1.2V and 0.9V LDOs).
> > 
> > Would it be appropriate to modify the qcom-refgen-regulator.c driver to
> > handle LDO voting for both the 1.2V and 0.9V supplies? In the regulator's
> > enable/disable callbacks, we could vote for and unvote these two LDOs
> > instead of performing register operations.
> 
> Wait, so you want to associate the MMIO-controlled refgen's driver with
> a dummy regulator that takes 2 supplies? I didn't catch that part earlier,
> that's not great..
> 
> Or do we actually have access to the MMIO of *this* refgen and can control

I can't find related info in any documentation.

> it (except we don't do that today because X Y Z)?
>

But even if we could find registers to enable/disable the refgen block,
the two LDOs (1.2V and 0.9V) would still need to be voted/unvoted manually
since they're separate power rails that feed the refgen.

I searched through the drivers/regulator/ directory and couldn't find any
existing examples where a regulator driver enables/disables other
regulators in its own enable/disable callbacks. This pattern doesn't seem
to be commonly used in the kernel.

So seems like we have to vote this two LDOs in phy driver.

- Qiang Yu
> Konrad