Hi Greg, et al, Userspace can mmap PCI device memory via the resourceN files in sysfs, which use pci_mmap_resource(). I think this path is unaware of power management, so the device may be runtime-suspended, e.g., it may be in D1, D2, or D3, where it will not respond to memory accesses. Userspace accesses while the device is suspended will cause PCI errors, so I think we need something like the patch below. But this isn't sufficient by itself because we would need a corresponding pm_runtime_put() when the mapping goes away. Where should that go? Or is there a better way to do this? diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 6d27475e39b2..aab7a47679a7 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1173,6 +1173,7 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr, mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io; + pm_runtime_get_sync(pdev); return pci_mmap_resource_range(pdev, bar, vma, mmap_type, write_combine); }
