Re: [PATCH] PCI: qcom: Power on pwrctrl devices for firmware-managed hosts

[Manivannan Sadhasivam]

On 2026-11-06 10:24 +0800, Zhangfei Gao wrote:
> On Thu, Nov 5, 2026 at 10:37 PM Manivannan Sadhasivam <mani@xxxxxxxxxx> wrote:
> >
> > On Thu, Nov 05, 2026 at 06:15:21PM +0800, Zhangfei Gao wrote:
> > > commit b921aa3f8dec ("PCI/pwrctrl: Switch to pwrctrl create, power
> > > on/off, destroy APIs") switched PCI pwrctrl users to explicit create and
> > > power control APIs, but only added the calls to the regular DesignWare
> > > host initialization path.
> > >
> > > Firmware-managed hosts bypass that path and probe the ECAM host bridge
> > > directly. Endpoints already powered by firmware, such as NVMe devices,
> > > remain discoverable. Endpoints that rely on Linux pwrctrl and pwrseq,
> > > such as WCN7850, remain powered off and cannot be discovered.
> > >
> >
> > NACK. For FW initialized platforms, FW should power on the Endpoints before
> > booting Linux.
> 
> Thanks Mani for the clarification.
> 
>   To confirm, for a firmware-initialized PCIe host, is the platform
>   firmware expected to perform the complete board-level Endpoint power
>   sequence as well, rather than only initializing the PCIe controller?
> 

Yes. By the time the Root Complex power domain gets turned on (which happens
before the controller driver probe), both the controller and Endpoint should be
ready.

>   On this platform, WCN7850 requires PMAU0102-E GPIOs 6/7/8 to enable its
>   power rails and GPIO10 for WLAN_EN. Should firmware assert these GPIOs
>   before Linux probes the ECAM host bridge and keep the Endpoint powered,
>   including across suspend/resume as appropriate?
> 
>   If so, we will drop this driver change and coordinate the required
>   platform firmware update.
> 

Yes. All the initialization required to power on the Endpoint should be done
by the firmware when the SCMI power domain for RC gets enabled. And when the
controller driver probes and scans the bus, the device should be visibile.

- Mani