mirror of
https://github.com/torvalds/linux.git
synced 2024-11-17 09:31:50 +00:00
3bfd659bae
ACPI identifies peer ports by setting their 'group_token' and 'group_position' _PLD data to the same value. If a platform has tier mismatch [1] , ACPI can override the default (USB3 defined) peer port association for internal hubs. External hubs follow the default peer association scheme. Location data is cached as an opaque cookie in usb_port_location data. Note that we only consider the group_token and group_position attributes from the _PLD data as ACPI specifies that group_token is a unique identifier. When we find port location data for a port then we assume that the firmware will also describe its peer port. This allows the implementation to only ever set the peer once. This leads to a question about what happens when a pm runtime event occurs while the peer associations are still resolving. Since we only ever set the peer information once, a USB3 port needs to be prevented from suspending while its ->peer pointer is NULL (implemented in a subsequent patch). There is always the possibility that firmware mis-identifies the ports, but there is not much the kernel can do in that case. [1]: xhci 1.1 appendix D figure 131 [2]: acpi 5 section 6.1.8 [alan]: don't do default peering when acpi data present Suggested-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|---|---|---|
| .. | ||
| buffer.c | ||
| config.c | ||
| devices.c | ||
| devio.c | ||
| driver.c | ||
| endpoint.c | ||
| file.c | ||
| generic.c | ||
| hcd-pci.c | ||
| hcd.c | ||
| hub.c | ||
| hub.h | ||
| Kconfig | ||
| Makefile | ||
| message.c | ||
| notify.c | ||
| otg_whitelist.h | ||
| port.c | ||
| quirks.c | ||
| sysfs.c | ||
| urb.c | ||
| usb-acpi.c | ||
| usb.c | ||
| usb.h | ||