Re: [PATCH 1/2] PCI: apple: Integrate pwrctrl API

[Manivannan Sadhasivam]

On Tue, Jul 14, 2026 at 06:57:11PM +0200, Yureka Lilian wrote:
> 
> On 7/9/26 14:29, Manivannan Sadhasivam wrote:
> > On Tue, Jul 07, 2026 at 02:58:39PM +0100, Marc Zyngier wrote:
> > > On Tue, 07 Jul 2026 13:04:21 +0100,
> > > Yureka Lilian <yureka@xxxxxxxxxxxxxx> wrote:
> > > > On 7/7/26 11:25, Marc Zyngier wrote:
> > > > > On Mon, 06 Jul 2026 23:38:27 +0100,
> > > > > Yureka Lilian <yureka@xxxxxxxxxxxxxx> wrote:
> > > > > > Integrate the PCI pwrctrl framework into the Apple PCIe host driver to
> > > > > > provide standardized power management for PCI devices.
> > > > > > 
> > > > > > Notably, this allows enabling powering on the WiFi, SD card reader on
> > > > > > various Macs by means of the pwrctrl framework before probing the ports.
> > > > > > 
> > > > > > Previously, a custom solution for powering on the WiFi and SD card
> > > > > > reader was proposed[1], but we can now use the new pci-pwrctrl-generic
> > > > > > driver for this purpose.
> > > > > > 
> > > > > > Link[1]: https://lore.kernel.org/lkml/20220502093832.32778-4-marcan@xxxxxxxxx/
> > > > > > 
> > > > > nit: this paragraph and the accompanying link don't belong in the
> > > > > commit message and should be moved below the --- mark or even better,
> > > > > to the cover letter.
> > > > ack, will leave it out of the commit message of the individual commit in v2
> > > > > > Signed-off-by: Yureka Lilian <yureka@xxxxxxxxxxxxxx>
> > > > > > ---
> > > > > >    drivers/pci/controller/Kconfig      |  1 +
> > > > > >    drivers/pci/controller/pcie-apple.c | 16 ++++++++++++++++
> > > > > >    2 files changed, 17 insertions(+)
> > > > > > 
> > > > > > diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> > > > > > index 2247709ef6d6..af64630d28fa 100644
> > > > > > --- a/drivers/pci/controller/Kconfig
> > > > > > +++ b/drivers/pci/controller/Kconfig
> > > > > > @@ -46,6 +46,7 @@ config PCIE_APPLE
> > > > > >    	depends on OF
> > > > > >    	depends on PCI_MSI
> > > > > >    	select PCI_HOST_COMMON
> > > > > > +	select PCI_PWRCTRL_GENERIC
> > > > > >    	select IRQ_MSI_LIB
> > > > > >    	help
> > > > > >    	  Say Y here if you want to enable PCIe controller support on Apple
> > > > > > diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> > > > > > index c2cffc0659f4..db038a9d4831 100644
> > > > > > --- a/drivers/pci/controller/pcie-apple.c
> > > > > > +++ b/drivers/pci/controller/pcie-apple.c
> > > > > > @@ -30,6 +30,7 @@
> > > > > >    #include <linux/msi.h>
> > > > > >    #include <linux/of_irq.h>
> > > > > >    #include <linux/pci-ecam.h>
> > > > > > +#include <linux/pci-pwrctrl.h>
> > > > > >      #include "pci-host-common.h"
> > > > > >    @@ -825,6 +826,21 @@ static int apple_pcie_init(struct
> > > > > > pci_config_window *cfg)
> > > > > >    	if (WARN_ON(!pcie))
> > > > > >    		return -ENOENT;
> > > > > >    +	ret = pci_pwrctrl_create_devices(pcie->dev);
> > > > > > +	if (ret) {
> > > > > > +		dev_err(pcie->dev, "Failed to create pwrctrl devices: %pe\n", ret);
> > > > > > +		return ret;
> > > > > > +	}
> > > > > > +
> > > > > > +	ret = pci_pwrctrl_power_on_devices(pcie->dev);
> > > > > > +	if (ret) {
> > > > > > +		if (ret != -EPROBE_DEFER) {
> > > > > > +			dev_err(pcie->dev, "Failed to power on devices: %pe\n", ret);
> > > > > > +			pci_pwrctrl_destroy_devices(pcie->dev);
> > > > > > +		}
> > > > > > +		return ret;
> > > > > > +	}
> > > > > > +
> > > > > Why is this done globally while the whole driver works on a per-port
> > > > > basis, and that the proposed DT updates are also per port?
> > > > pci_pwrctrl_power_on_devices takes a struct device as parameter, but
> > > > pcie-apple does not allocate device structs for the individual ports.
> > > > This could be changed of course. But since pci_pwrctrl_* operate on
> > > > the subnodes recursively, it works just fine this way.
> > > Works fine is one thing. Being consistent with the way the rest of the
> > > driver works is another. pci_pwrctrl_create_device() and
> > > pci_pwrctrl_power_on_device() appear to do exactly what would be
> > > required for a single port. They just needs to be exported made
> > > global/exported.
> > > 
> > I'm fine with exporting pci_pwrctrl_create_device() and
> > pci_pwrctrl_power_on_device() and calling them with per-port np.
> > 
> > - Mani
> 
> In theory I do agree this would work to power on the slots, and I can send a
> v2 of the patch doing it that way, but I don't quite understand yet how this
> fits better with the existing driver code: If this is the case, what is the
> difference between pcie-apple and pcie-qcom and why should pcie-qcom use the
> recursive function but pcie-apple not?
> 

For pcie-qcom, it needs to iterate through all PCI child nodes, not just the RP
as we have multiple nodes due to PCIe switch (and switches in some design). So
this per-port API wouldn't work there.

- Mani

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