Bug 195253
| Summary: | disabling PCIEASPM makes link speed drop from 5 GT/s to 2.5 GT/s | ||
|---|---|---|---|
| Product: | Drivers | Reporter: | Uwe Kleine-König (uwe+kernel) |
| Component: | PCI | Assignee: | drivers_pci (drivers_pci) |
| Status: | NEW --- | ||
| Severity: | normal | CC: | pali |
| Priority: | P1 | ||
| Hardware: | ARM | ||
| OS: | Linux | ||
| Kernel Version: | 4.9 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
| Attachments: |
lspci -vv with PCIEASPM=n
lspci -vv with PCIEASPM=y |
||
Created attachment 255761 [details]
lspci -vv with PCIEASPM=y
I saw similar syndromes on other Armada SoCs. It looks like that in this particular cases is link initialized only to 2.5 GT/s and "upgrade" to 5 GT/s is done after explicit link retraining. As PCIe ASPM during initialization is calling link retraining, it means that it "upgrades" link speed to 5 GT/s. But there are some cards which do not like link retraining and just crash when kernel do it explicitly. See bug #209833 and bug #192441. I guess that this is HW issue in Armada PCIe IP. |
Created attachment 255759 [details] lspci -vv with PCIEASPM=n Hello, on an Armada XP (i.e. arm) system disabling PCIEASPM results in different link speed. See attachments for lspci with and without PCIEASPM. Best regards Uwe