On Fri, Nov 15, 2019 at 03:34:23PM +0530, Vidya Sagar wrote: > On 11/15/2019 12:06 AM, Bjorn Helgaas wrote: > > On Wed, Nov 13, 2019 at 12:20:43PM +0100, Thierry Reding wrote: > > > On Tue, Nov 12, 2019 at 12:58:44PM -0600, Bjorn Helgaas wrote: > > > > > > > My question is whether this wait should be connected somehow with > > > > platform_pci_set_power_state(). It sounds like the tegra host > > > > controller driver already does the platform-specific delays, and I'm > > > > not sure it's reasonable for platform_pci_set_power_state() to do the > > > > CRS polling. Maybe something like this? I'd really like to get > > > > Rafael's thinking here. > > > > > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > > > > index e7982af9a5d8..052fa316c917 100644 > > > > --- a/drivers/pci/pci.c > > > > +++ b/drivers/pci/pci.c > > > > @@ -964,9 +964,14 @@ void pci_refresh_power_state(struct pci_dev *dev) > > > > */ > > > > void pci_power_up(struct pci_dev *dev) > > > > { > > > > + pci_power_state_t prev_state = dev->current_state; > > > > + > > > > if (platform_pci_power_manageable(dev)) > > > > platform_pci_set_power_state(dev, PCI_D0); > > > > + if (prev_state == PCI_D3cold) > > > > + pci_dev_wait(dev, "D3cold->D0", PCIE_RESET_READY_POLL_MS); > > Is there any specific reason why should there be a check for the > state? In Tegra series, I observe that, by the time execution comes > to this point, prev_state is PCI_D3Hot and in Tegra194 particularly, > it is PCI_D0 because the host controller driver explicitly keeps the > downstream devices in PCI_D0 state as a work around for one of the > Tegra194 specific issues. I think you're right, we probably should not try to check "prev_state" here because we can't rely on that being accurate. On Tegra, I assume suspend puts the PCIe devices in D3hot, then when we suspend the RC itself, it looks like tegra_pcie_pm_suspend() actually turns off the power, so the PCIe devices probably go to D3cold but nothing updates their dev->current_state, so it's probably still PCI_D3hot. On Tegra194, the same probably happens, except that when we suspend the RC itself, tegra_pcie_downstream_dev_to_D0() puts the PCIe devices back in D0 (updating their dev->current_state to PCI_D0), and then we turn off the power, so they probably also end up in D3cold but with dev_current_state still set to PCI_D0. > So, I feel the check for current_state may not be need here(?) I think you're right. We can't tell what dev->current_state is when we enter pci_power_up(). Bjorn