Re: [PATCH v3 2/2] phy: qcom-snps-femto-v2: Add support for SA8255P

[Manivannan Sadhasivam]

On 2026-10-02 11:41 +0200, Mattijs Korpershoek wrote:
> From: Sriram Dash <quic_sriramd@xxxxxxxxxxx>
> 
> The Qualcomm automotive SA8255p SoC relies on firmware to configure
> platform resources, including clocks, interconnects and TLMM.
> The driver requests resources operations over SCMI using power protocols.
> 
> The SCMI power protocol enables or disables resources like clocks,
> interconnect paths, and TLMM (GPIOs) using runtime PM framework APIs,
> such as resume/suspend, to control power on/off.
> 
> Power domain "core" controls the GDSC, resets, and TLMM (GPIOs)
> whereas power domain "transfer" controls clocks and interconnects.
> 

This is not consistent with other SCMI based drivers. Most of them are using
'power' and 'perf' power domains, not 'core', 'transfer'.

Why are these discrete powers domains be required? In my point of view, the PHY
should have only one power domain for controlling power and be done with it. If
you start having these fine grain controls over the resources from SCMI clients,
then it defeats the purpose of the SCMI based firmware abstraction design.

> In this variant, two disjoint sets of resources are modeled against
> the power domain suppliers which can be turned on/off to achieve modeled
> device states. Two modeled low power states d1 and d3 are supported.
> 
> transition: d0 <--> d3  :: both core and transfer suppliers
> transition: d0 <--> d1  :: only transfer supplier
> 

What are these transition levels and who defines these? We cannot have different
SCMI drivers inventing these kind of independent low power modes.

- Mani