[+cc Rafael, linux-pm for a PM perspective]
On Mon, Jun 11, 2018 at 04:29:18PM -0600, Keith Busch wrote:
> A bridge that supports D3 but not hotplug will be subject to runtime
> power management placing it in a non-operation power state if it doesn't
> have any devices attached. This patch will prevent this power management
> during error recovery so that the rescan at the end may be successful.
I assume you're seeing a problem that's fixed by this patch?
I'm not very familiar with the pm_runtime_*() interfaces. The fact
that drivers/pci/ only contains two calls to pm_runtime_forbid() and
two to pm_runtime_allow() (one in a quirk) makes me wonder if this is
the right approach.
Do we need something similar in other enumeration paths, e.g.,
boot-time enumeration, hot-add, sysfs "rescan" entry, etc?
> Cc: Oza Pawandeep <poza@xxxxxxxxxxxxxx>
> Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
> ---
> drivers/pci/pcie/err.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
> index f7ce0cb0b0b7..247b6ce14f0d 100644
> --- a/drivers/pci/pcie/err.c
> +++ b/drivers/pci/pcie/err.c
> @@ -16,6 +16,7 @@
> #include <linux/kernel.h>
> #include <linux/errno.h>
> #include <linux/aer.h>
> +#include <linux/pm_runtime.h>
> #include "portdrv.h"
> #include "../pci.h"
>
> @@ -294,6 +295,7 @@ void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service)
> udev = dev->bus->self;
>
> parent = udev->subordinate;
> + pm_runtime_forbid(&udev->dev);
> pci_lock_rescan_remove();
> list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
> bus_list) {
> @@ -329,6 +331,7 @@ void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service)
> }
>
> pci_unlock_rescan_remove();
> + pm_runtime_allow(&udev->dev);
> }
>
> /**
> --
> 2.14.3
>
