svn commit: r367359 - stable/12/sys/dev/pci

[martin at vx.sk]

  I am encountering a problem with hw.pci.enable_aspm:

System: ASUS RS500A-E10-RS12U
CPU: AMD EPYC 7502 32-Core.
NVMe drive model: Micron 9300 PRO
Number of NVMe drives: 10

  Using X2APIC

When hw.pci.enable_aspm is enabled, PCIe hot plug of Micron NVMe  
drives does not work (including detection on boot) and the system  
reports the following errors for the vast majority of the drives:

  Nov 13 15:11:30 xxx kernel: pcib9: Timed out waiting for Data Link  
Layer Active
Nov 13 15:12:17 xxx kernel: pcib30: Timed out waiting for Data Link  
Layer Active
Nov 13 15:12:44 xxx kernel: pcib29: Timed out waiting for Data Link  
Layer Active
Nov 13 15:13:04 xxx kernel: pcib11: Timed out waiting for Data Link  
Layer Active
...

Flipping the tunable back to 0 workarounds the problem.

Reproduced both on latest head and stable/12.

Best regards,
mm

Quoting Alexander Motin <mav at freebsd.org>:

> Author: mav
> Date: Thu Nov  5 02:57:40 2020
> New Revision: 367359
> URL: https://svnweb.freebsd.org/changeset/base/367359
>
> Log:
> MFC r364038: Enable hw.pci.enable_aspm tunable by default.
>
> While effects on power saving is only a guess, effects on hot-plug are
> clearly visible.  Lets try to enable it and see what happen.
>
> Modified:
> stable/12/sys/dev/pci/pci.c
> Directory Properties:
> stable/12/   (props changed)
>
> Modified: stable/12/sys/dev/pci/pci.c
> ==============================================================================
> --- stable/12/sys/dev/pci/pci.c        Thu Nov  5 02:12:33 2020       
>   (r367358)
> +++ stable/12/sys/dev/pci/pci.c        Thu Nov  5 02:57:40 2020       
>   (r367359)
> @@ -411,7 +411,7 @@ static int pci_enable_ari = 1;
> SYSCTL_INT(_hw_pci, OID_AUTO, enable_ari, CTLFLAG_RDTUN, &pci_enable_ari,
>     0, "Enable support for PCIe Alternative RID Interpretation");
>
> -int pci_enable_aspm;
> +int pci_enable_aspm = 1;
> SYSCTL_INT(_hw_pci, OID_AUTO, enable_aspm, CTLFLAG_RDTUN,  
> &pci_enable_aspm,    0, "Enable support for PCIe Active State Power  
> Management");