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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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c521b014cd
Use usleep_range() instead of udelay() while waiting for a VPD access to complete. This is not a performance path, so no need to hog the CPU. Rationale for usleep_range() parameters: We clear PCI_VPD_ADDR_F for a read (or set it for a write), then wait for the device to change it. For a device that updates PCI_VPD_ADDR between our config write and subsequent config read, we won't sleep at all and can get the device's maximum rate. Sleeping a minimum of 10 usec per 4-byte access limits throughput to about 400Kbytes/second. VPD is small (32K bytes at most), and most devices use only a fraction of that. We back off exponentially up to 1024 usec per iteration. If we reach 1024, we've already waited up to 1008 usec (16 + 32 + ... + 512), so if we miss an update and wait an extra 1024 usec, we can still get about 1/2 of the device's maximum rate. Tested-by: Shane Seymour <shane.seymour@hpe.com> Tested-by: Babu Moger <babu.moger@oracle.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Hannes Reinecke <hare@suse.com> |
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|---|---|---|
| .. | ||
| host | ||
| hotplug | ||
| pcie | ||
| access.c | ||
| ats.c | ||
| bus.c | ||
| host-bridge.c | ||
| hotplug-pci.c | ||
| htirq.c | ||
| iov.c | ||
| irq.c | ||
| Kconfig | ||
| Makefile | ||
| msi.c | ||
| of.c | ||
| pci-acpi.c | ||
| pci-driver.c | ||
| pci-label.c | ||
| pci-stub.c | ||
| pci-sysfs.c | ||
| pci.c | ||
| pci.h | ||
| probe.c | ||
| proc.c | ||
| quirks.c | ||
| remove.c | ||
| rom.c | ||
| search.c | ||
| setup-bus.c | ||
| setup-irq.c | ||
| setup-res.c | ||
| slot.c | ||
| syscall.c | ||
| vc.c | ||
| vpd.c | ||
| xen-pcifront.c | ||