On Thu, Jun 26, 2025 at 03:17:48PM -0700, Sean Christopherson wrote:
> On Wed, Jun 25, 2025, Bjorn Helgaas wrote:
> > On Tue, Jun 24, 2025 at 10:16:37AM -0700, Sean Christopherson wrote:
> > > +void pci_pm_init(struct pci_dev *dev)
> > > +{
> > > + u16 status;
> > > +
> > > + device_enable_async_suspend(&dev->dev);
> > > + dev->wakeup_prepared = false;
> > > +
> > > + dev->pm_cap = 0;
> > > + dev->pme_support = 0;
> > > +
> > > + /*
> > > + * Note, support for the PCI PM spec is optional for legacy PCI devices
> > > + * and for VFs. Continue on even if no PM capabilities are supported.
> > > + */
> > > + __pci_pm_init(dev);
> > >
> > > pci_read_config_word(dev, PCI_STATUS, &status);
> > > if (status & PCI_STATUS_IMM_READY)
> > > dev->imm_ready = 1;
> >
> > I would rather just move this PCI_STATUS read to somewhere else. I
> > don't think there's a great place to put it. We could put it in
> > set_pcie_port_type(), which is sort of a grab bag of PCIe-related
> > things.
> >
> > I don't know if it's necessarily even a PCIe-specific thing, but it
> > would be unexpected if somebody made a conventional PCI device that
> > set it, since the bit was reserved (and should be zero) in PCI r3.0
> > and defined in PCIe r4.0.
> >
> > Maybe we should put it in pci_setup_device() close to where we call
> > pci_intx_mask_broken()?
>
> Any reason not to throw it in pci_init_capabilities()? That has the
> advantage of minimizing the travel distance, e.g. to avoid
> introducing a goof similar to what happened with 4d4c10f763d7 ("PCI:
> Explicitly put devices into D0 when initializing").
The only reason I suggested doing it earlier was to enable a potential
pci_find_capability() optimization. But this could easily be moved
if/when that happens, so I think the patch below would be fine.
> E.g. something silly like this? Or maybe pci_misc_init() or so?
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 9e42090fb108..4a1ba5c017cd 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3205,7 +3205,6 @@ void pci_pm_power_up_and_verify_state(struct pci_dev *pci_dev)
> void pci_pm_init(struct pci_dev *dev)
> {
> int pm;
> - u16 status;
> u16 pmc;
>
> device_enable_async_suspend(&dev->dev);
> @@ -3266,9 +3265,6 @@ void pci_pm_init(struct pci_dev *dev)
> pci_pme_active(dev, false);
> }
>
> - pci_read_config_word(dev, PCI_STATUS, &status);
> - if (status & PCI_STATUS_IMM_READY)
> - dev->imm_ready = 1;
> poweron:
> pci_pm_power_up_and_verify_state(dev);
> pm_runtime_forbid(&dev->dev);
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 4b8693ec9e4c..d33b8af37247 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2595,6 +2595,15 @@ void pcie_report_downtraining(struct pci_dev *dev)
> __pcie_print_link_status(dev, false);
> }
>
> +static void pci_imm_ready_init(struct pci_dev *dev)
> +{
> + u16 status;
> +
> + pci_read_config_word(dev, PCI_STATUS, &status);
> + if (status & PCI_STATUS_IMM_READY)
> + dev->imm_ready = 1;
> +}
> +
> static void pci_init_capabilities(struct pci_dev *dev)
> {
> pci_ea_init(dev); /* Enhanced Allocation */
> @@ -2604,6 +2613,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
> /* Buffers for saving PCIe and PCI-X capabilities */
> pci_allocate_cap_save_buffers(dev);
>
> + pci_imm_ready_init(dev); /* Immediate Ready */
> pci_pm_init(dev); /* Power Management */
> pci_vpd_init(dev); /* Vital Product Data */
> pci_configure_ari(dev); /* Alternative Routing-ID Forwarding */
