Hi, all,
On Fri, Sep 11, 2020 at 4:32 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> [+cc Tiezhu]
>
> On Sat, Aug 01, 2020 at 03:49:40PM +0800, Huacai Chen wrote:
> > Use separate remove()/shutdown() callback, and don't disable pci device
> > during shutdown. This can avoid some poweroff/reboot failures.
> >
> > The poweroff/reboot failures can easily reproduce on Loongson platforms.
> > I think this is not a Loongson-specific problem, instead, is a problem
> > related to some specific PCI hosts. On some x86 platforms, radeon/amdgpu
> > devices can cause the same problem, and commit faefba95c9e8ca3a523831c2e
> > ("drm/amdgpu: just suspend the hw on pci shutdown") can resolve it.
> >
> > Radeon driver is more difficult than amdgpu due to its confusing symbol
> > names, and I have maintained an out-of-tree patch for a long time [1].
> > Recently, we found more and more devices can cause the same problem, and
> > it is very difficult to modify all problematic drivers as radeon/amdgpu
> > does. So, I think modify the PCIe port driver is a simple and effective
> > way.
>
> Sounds plausible, but I don't know what the actual problem is, other
> than "poweroff/reboot doesn't work, and this patch 'fixes' it".
After all discussions (including those in the other thread), I think
the actual problem is "every driver should implement their shutdown
callback correctly as radeon/amdgpu does, otherwise there will be
poweroff failures because of device's BUS MASTER".
So, I think I should give two patches, the first remove the "remove"
callback, and the second just simply remove the "pci_disable_device()"
instead of modifying a ton of drivers, right?
Huacai
>
> > [1] https://github.com/chenhuacai/linux/commit/6612f9c1fc290d42a14618ce9a7d03014d8ebb1a
> >
> > Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
> > ---
> > drivers/pci/pcie/portdrv.h | 2 +-
> > drivers/pci/pcie/portdrv_core.c | 6 ++++--
> > drivers/pci/pcie/portdrv_pci.c | 15 +++++++++++++--
> > 3 files changed, 18 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
> > index af7cf23..22ba7b9 100644
> > --- a/drivers/pci/pcie/portdrv.h
> > +++ b/drivers/pci/pcie/portdrv.h
> > @@ -123,7 +123,7 @@ int pcie_port_device_resume(struct device *dev);
> > int pcie_port_device_runtime_suspend(struct device *dev);
> > int pcie_port_device_runtime_resume(struct device *dev);
> > #endif
> > -void pcie_port_device_remove(struct pci_dev *dev);
> > +void pcie_port_device_remove(struct pci_dev *dev, bool disable);
> > int __must_check pcie_port_bus_register(void);
> > void pcie_port_bus_unregister(void);
> >
> > diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
> > index 50a9522..aa165be 100644
> > --- a/drivers/pci/pcie/portdrv_core.c
> > +++ b/drivers/pci/pcie/portdrv_core.c
> > @@ -487,11 +487,13 @@ EXPORT_SYMBOL_GPL(pcie_port_find_device);
> > * Remove PCI Express port service devices associated with given port and
> > * disable MSI-X or MSI for the port.
> > */
> > -void pcie_port_device_remove(struct pci_dev *dev)
> > +void pcie_port_device_remove(struct pci_dev *dev, bool disable)
> > {
> > device_for_each_child(&dev->dev, NULL, remove_iter);
> > pci_free_irq_vectors(dev);
> > - pci_disable_device(dev);
> > +
> > + if (disable)
> > + pci_disable_device(dev);
> > }
>
> portdrv can only be built statically (not as a module), and I don't
> think there's value in being able to unbind it. So I think we should
> remove its .remove() method. That would be a separate patch, of
> course, but it should make this one quite a bit simpler.
>
> > /**
> > diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
> > index 3acf151..fcd3d2e 100644
> > --- a/drivers/pci/pcie/portdrv_pci.c
> > +++ b/drivers/pci/pcie/portdrv_pci.c
> > @@ -142,7 +142,18 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
> > pm_runtime_dont_use_autosuspend(&dev->dev);
> > }
> >
> > - pcie_port_device_remove(dev);
> > + pcie_port_device_remove(dev, true);
> > +}
> > +
> > +static void pcie_portdrv_shutdown(struct pci_dev *dev)
> > +{
> > + if (pci_bridge_d3_possible(dev)) {
> > + pm_runtime_forbid(&dev->dev);
> > + pm_runtime_get_noresume(&dev->dev);
> > + pm_runtime_dont_use_autosuspend(&dev->dev);
> > + }
>
> I admit to being ignorant about how all this PM stuff works. A
> comment here about what's going on and why we need to check
> pci_bridge_d3_possible() would be useful.
>
> > + pcie_port_device_remove(dev, false);
> > }
> >
> > static pci_ers_result_t pcie_portdrv_error_detected(struct pci_dev *dev,
> > @@ -211,7 +222,7 @@ static struct pci_driver pcie_portdriver = {
> >
> > .probe = pcie_portdrv_probe,
> > .remove = pcie_portdrv_remove,
> > - .shutdown = pcie_portdrv_remove,
> > + .shutdown = pcie_portdrv_shutdown,
> >
> > .err_handler = &pcie_portdrv_err_handler,
> >
> > --
> > 2.7.0
> >
