Re: [PATCH V2 1/8] PCI: imx6: Add skip_pwrctrl_off flag support

[Manivannan Sadhasivam]

On Thu, Jun 25, 2026 at 07:25:46AM +0000, Sherry Sun wrote:
> > Subject: Re: [PATCH V2 1/8] PCI: imx6: Add skip_pwrctrl_off flag support
> > 
> > On Wed, Jun 24, 2026 at 07:09:26AM +0000, Sherry Sun wrote:
> > > > Subject: Re: [PATCH V2 1/8] PCI: imx6: Add skip_pwrctrl_off flag
> > > > support
> > > >
> > > > On Tue, Jun 23, 2026 at 11:07:28AM +0800, Sherry Sun (OSS) wrote:
> > > > > From: Sherry Sun <sherry.sun@xxxxxxx>
> > > > >
> > > > > Use dw_pcie_rp::skip_pwrctrl_off to avoid powering off devices
> > > > > during suspend to preserve wakeup capability of the devices and
> > > > > also not to power on the devices in the init path.
> > > > > This allows controller power-off to be skipped when some devices(e.g.
> > > > > M.2 cards key E without auxiliary power) required to support PCIe
> > > > > L2 link state and wake-up mechanisms.
> > > > >
> > > > > Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx>
> > > > > ---
> > > > >  drivers/pci/controller/dwc/pci-imx6.c | 36
> > > > > +++++++++++++++++----------
> > > > >  1 file changed, 23 insertions(+), 13 deletions(-)
> > > > >
> > > > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > > > > b/drivers/pci/controller/dwc/pci-imx6.c
> > > > > index 0fa716d1ed75..ff5a9565dbbf 100644
> > > > > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > > > > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > > > > @@ -1382,16 +1382,20 @@ static int imx_pcie_host_init(struct
> > > > > dw_pcie_rp
> > > > *pp)
> > > > >  		}
> > > > >  	}
> > > > >
> > > > > -	ret = pci_pwrctrl_create_devices(dev);
> > > > > -	if (ret) {
> > > > > -		dev_err(dev, "failed to create pwrctrl devices\n");
> > > > > -		goto err_reg_disable;
> > > > > +	if (!pci->suspended) {
> > > > > +		ret = pci_pwrctrl_create_devices(dev);
> > > >
> > > > Is possible move pci_pwrctrl_create_devices() of
> > > > pci_pwrctrl_create_devices
> > > >
> > > > and call it direct at probe() function, like other regulator_get function.
> > > >
> > >
> > > Hi Frank,
> > > That makes sense. However, if we move pci_pwrctrl_create_devices () to
> > > probe(), we may need to add the following goto err_pwrctrl_destroy
> > > path in imx_pcie_probe() to properly handle errors from
> > > pci_pwrctrl_power_on_devices(), is that acceptable?
> > 
> > Can you add a API devm_pci_pwrctrl_create_devices() ?
> > 
> 
> Hi Frank, we cannot unconditionally destroy the pwrctrl devices
> when probing fails by using devm API.
> Since we need to check the return value of
> pci_pwrctrl_power_on_devices() for example EPROBE_DEFER to decide
> whether to destroy the pwrctrl devices to avoid the deferred probe loop.
> 
> You can find more related discussion here.
> https://lore.kernel.org/all/tutxwjciedqoje5wxvtin4h637auni5zzpvb7rtfg4uticxoux@yfl6xg7oht7t/
> 

Yes. Ideally we should try to do a blocking wait in the pwrctrl core until all
the pwrctrl drivers are probed, instead of deferring probe. Hopefully, I'll get
to it soon.

- Mani

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