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PCI/ACPI: Optimize device state transition delays

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The PCI "ACPI additions for FW latency optimizations" ECN (link below)
defines two functions in the PCI _DSM:

  Function 8, "Reset Delay," applies to the entire hierarchy below a PCI
  host bridge.  If it returns one, the OS may assume that all devices in
  the hierarchy have already completed power-on reset delays.

  Function 9, "Device Readiness Durations," applies only to the object
  where it is located.  It returns delay durations required after various
  events if the device requires less time than the spec requires.  Delays
  from this function take precedence over the Reset Delay function.

Add support for Reset Delay and part of Device Readiness Durations.

[bhelgaas: changelog, comments]
Link: https://www.pcisig.com/specifications/conventional/pci_firmware/ECN_fw_latency_optimization_final.pdf
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Aaron Lu
2015-03-25 14:37:06 +08:00
committed by Bjorn Helgaas
parent 3390e0850b
commit e33caa82e2
3 changed files with 77 additions and 0 deletions
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include/linux/pci.h
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@@ -406,6 +406,7 @@ struct pci_host_bridge {
struct list_head windows; /* resource_entry */
void (*release_fn)(struct pci_host_bridge *);
void *release_data;
unsigned int ignore_reset_delay:1; /* for entire hierarchy */
};
#define to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)