Re: [PATCH v2 3/4] arm64: dts: qcom: x1-dell-thena: mark l12b and l15b always-on

[Val Packett]

On 5/20/26 10:09 PM, Michael Scott wrote:
> The l12b and l15b supplies are used by components that are not (fully)
> described (and some never will be) and must never be disabled.
>
> Mark the regulators as always-on to prevent them from being disabled,
> for example, when consumers probe defer or suspend.
>
> Note that these supplies currently have no consumers described in
> mainline for dell-thena beyond the audio codec (vdd-buck/vdd-rxtx/
> vdd-io on wcd938x), which can release them when the codec goes idle.
> The board-level gpio-fixed regulators that feed the Type-C retimer's
> VDDIO and other rails are not described with a vin-supply link, so
> the kernel cannot keep their parent LDOs alive on its own.
>
> This mirrors the same change Johan Hovold applied to every other
> X1E80100 board in a March 2025 series; commit 63169c07d740
> ("arm64: dts: qcom: x1e80100-dell-xps13-9345: mark l12b and l15b always-on")
> is representative. The dell-thena board file was introduced four months
> later and did not inherit that change; this patch closes the gap.

Acked-by: Val Packett <val@xxxxxxxxxxxx>


Asked a friend who has totally legitimate access to the XPS schematics 
about what those components are:

L12B: IO_1P2/275mA
- MOSFETs and pullups on a bunch of I2C, PCIe CLKREQ/WAKE, etc.
- VDDIO for WSA speakers
- NVME_PLN_N_1P2 (Power Loss Notification?)
- bunch of VDD_PX pins on the SoC


L15B: IO_1P8/1.09A
- MOSFETs and pullups on eDP HPD, bunch of I2C, PCIe CLKREQ/WAKE, some 
INTR#/RESET#, SSD Load Switch, etc.
- VIN for Load Switch outputting retimer's VDDIO
- VDD_1P8 for WSA speakers
- VDDIO for power monitor ICs on IR_I2C


Yeahhh.. I think the load switches could potentially be modeled but the 
huge bunch of random pullups not so much. I wonder how Windows handles 
this. Maybe it could be in low-power mode when speakers are idle?

~val