[+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".
> [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
>
