d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add mostly dummy hw.pci.enable_aspm tunable.

Browse Source 
The only thing this tunable enables now is reporting to ACPI _OSC that
Active State Power Management and Clock Power Management Capability are
"supported" by the OS.

I've found that at least some Supermicro server boards do not allow OS
to support native PCIe hot-plug unless it reports those capabilities.
After spending significant time in PCIe specs I have found very little
motivation for that, and none of it applies to those motherboards, not
enabling ASPM themselves.  So unless OS explicitly wants to save power,
I see nothing for it to do there actually.

I guess it may get sense to support ASPM when we get Thunderbolt support.
Otherwise I have no system with PCIe hot-plug where power saving matters.

It would be nice to enable this by default, but I worry that it affect
power saving of some laptops, even though I haven't noticed that myself.
This commit is contained in:
mav 2020-06-26 19:55:11 +00:00
parent 8f9fe9a382
commit bd625a4888
3 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
sys/dev/acpica/acpi_pcib_acpi.c
View File

@ -326,6 +326,10 @@ acpi_pcib_osc(struct acpi_hpcib_softc *sc, uint32_t osc_ctl)
/* Support Field: Extended PCI Config Space, PCI Segment Groups, MSI */
cap_set[PCI_OSC_SUPPORT] = PCIM_OSC_SUPPORT_EXT_PCI_CONF |
PCIM_OSC_SUPPORT_SEG_GROUP | PCIM_OSC_SUPPORT_MSI;
/* Active State Power Management, Clock Power Management Capability */
if (pci_enable_aspm)
cap_set[PCI_OSC_SUPPORT] |= PCIM_OSC_SUPPORT_ASPM |
PCIM_OSC_SUPPORT_CPMC;
/* Control Field */
cap_set[PCI_OSC_CTL] = sc->ap_osc_ctl | osc_ctl;

4
sys/dev/pci/pci.c
View File

@ -408,6 +408,10 @@ 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;
SYSCTL_INT(_hw_pci, OID_AUTO, enable_aspm, CTLFLAG_RDTUN, &pci_enable_aspm,
0, "Enable support for PCIe Active State Power Management");
static int pci_clear_aer_on_attach = 0;
SYSCTL_INT(_hw_pci, OID_AUTO, clear_aer_on_attach, CTLFLAG_RWTUN,
&pci_clear_aer_on_attach, 0,

1
sys/dev/pci/pcivar.h
View File

@ -257,6 +257,7 @@ typedef struct {
} pcih2cfgregs;
extern uint32_t pci_numdevs;
extern int pci_enable_aspm;
/*
* The bitfield has to be stable and match the fields below (so that