Re: [PATCH v4 7/7] arm64: dts: qcom: mahua: Switch pcie5_phy ref clock to RPMH_CXO_CLK

[Qiang Yu]

On Tue, Jun 09, 2026 at 03:06:02PM +0200, Konrad Dybcio wrote:
> On 5/28/26 4:29 AM, Qiang Yu wrote:
> > PCIe5 PHY on Mahua gets refclk from CXO0 pad directly, so no QREF
> > clkref_en voting is required. Override the clock list to use RPMH_CXO_CLK
> > directly instead.
> 
> This is the last piece of the puzzle that this series is missing.
> There's no QREF clkref_en, but there is a refgen that needs to be
> powered. For PCIe5 on Mahua this would be L2F_E0 (0p9) and L4H_E0
> (1p2).
> 
> I think the easiest (laziest?) solution would be to add dummy clocks
> in the clkref driver and only toggle the required regulators. Another
> option is to defer back to individual drivers (such as PCIe QMPPHY).
> 
> I kinda like the "one central node to drive power" approach, but I'm
> not sure others agree, since it stretches truth just a tiny bit
> (although not as much as one would think since there are *some*
> controls for the transparent-to-the-OS hw pieces in these paths still
> in TCSR).. Dmitry, Krzysztof, would you object to that?
>

PCIe5 PHY on Mahua does not use QREF at all, so there is no refgen for
QREF either. The refgen supplies you mentioned are for the PCIe5 PHY
itself, not for QREF. For other PHYs that do use QREF, there are two
refgens: one for QREF (voted here in the TCSR clkref driver) and one for
the PHY (which should be voted in the PHY driver).

- Qiang Yu
> Konrad