On Fri, Nov 07, 2025 at 11:39:50AM +0530, Manivannan Sadhasivam wrote:
> On Thu, Nov 06, 2025 at 12:36:39PM -0600, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <[email protected]>
> >
> > Christian reported that f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and
> > ASPM states for devicetree platforms") broke booting on the A-EON X5000.
> >
> > Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for
> > devicetree platforms")
> > Fixes: df5192d9bb0e ("PCI/ASPM: Enable only L0s and L1 for devicetree
> > platforms"
> > )
> > Reported-by: Christian Zigotzky <[email protected]>
> > Link:
> > https://lore.kernel.org/r/[email protected]
> > Signed-off-by: Bjorn Helgaas <[email protected]>
> > ---
> > drivers/pci/quirks.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > index 214ed060ca1b..44e780718953 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -2525,6 +2525,18 @@ static void quirk_disable_aspm_l0s_l1(struct pci_dev
> > *dev)
> > */
> > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ASMEDIA, 0x1080,
> > quirk_disable_aspm_l0s_l1);
> >
> > +/*
> > + * Remove ASPM L0s and L1 support from cached copy of Link Capabilities so
> > + * aspm.c won't try to enable them.
> > + */
> > +static void quirk_disable_aspm_l0s_l1_cap(struct pci_dev *dev)
> > +{
> > + dev->lnkcap &= ~PCI_EXP_LNKCAP_ASPM_L0S;
> > + dev->lnkcap &= ~PCI_EXP_LNKCAP_ASPM_L1;
> > + pci_info(dev, "ASPM: L0s L1 removed from Link Capabilities to work
> > around device defect\n");
> > +}
> > +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_FREESCALE, 0x0451,
> > quirk_disable_aspm_l0s_l1_cap);
>
> From the commit message of the earlier version [1] you shared:
>
> Removing advertised features prevents aspm.c from enabling them, even if
> users try to enable them via sysfs or by building the kernel with
> CONFIG_PCIEASPM_POWERSAVE or CONFIG_PCIEASPM_POWER_SUPERSAVE.
>
> Going by this reasoning, shouldn't we be doing this for the other
> quirks (quirk_disable_aspm_l0s_l1/quirk_disable_aspm_l0s) as well?
Yes, probably so. I was thinking that could be done later to limit
the scope of v6.18 changes, but since we're enabling L0s/L1 when we
didn't before, we should probably update those quirks too.
I was hesitant because quirk_disable_aspm_l0s_l1_cap() isn't quite the
same as quirk_disable_aspm_l0s_l1() because pci_disable_link_state()
turns off states that are currently enabled and also prevents them
from being enabled in the future, but quirk_disable_aspm_l0s_l1_cap()
essentially just clears Link Capability bits.
But if we clear a Link Capability bit for a state that was already
enabled by firmware:
- If POLICY_DEFAULT or POLICY_PERFORMANCE, I think we'll disable the
state during enumeration:
pci_scan_slot
pcie_aspm_init_link_state
pcie_aspm_init_link_state
if (POLICY_DEFAULT || POLICY_PERFORMANCE)
pcie_config_aspm_path
- If POLICY_POWERSAVE or POLICY_POWER_SUPERSAVE, I think we'll
disable it in pci_enable_device():
pci_enable_device
do_pci_enable_device
pcie_aspm_powersave_config_link
if (POLICY_POWERSAVE || POLICY_POWER_SUPERSAVE)
pcie_config_aspm_path
If firmware enabled the state, it must at least be safe enough to
boot, and we should eventually disable it regardless of how the kernel
was built.
Bjorn
