On Fri, 16 Oct 2026, Manivannan Sadhasivam wrote: > On Wed, Oct 14, 2026 at 03:51:17PM -0500, Bjorn Helgaas wrote: > > [+cc Emmanuel, Matthew] > > > > On Wed, Jul 08, 2026 at 04:30:14PM +0200, Manivannan Sadhasivam wrote: > > > Hi, > > > > > > This series converts the atheros WLAN drivers (ath10k/ath11k/ath12k) to > > > use the PCI core ASPM APIs for enabling/disabling ASPM instead of writing > > > to the LNKCTL register directly. Touching LNKCTL behind the PCI core's > > > back leaves the ASPM service driver's view of the link state out of sync > > > with the hardware, which is not nice. > > > > > > The catch is that these drivers save the currently enabled ASPM states, > > > disable ASPM before firmware download, and restore the saved states > > > afterwards. pci_enable_link_state() cannot restore states that were > > > disabled via pci_disable_link_state() or blacklisted during init (like > > > the pre-1.1 device blacklist, which is only meant to be overridden with > > > pcie_aspm=force), and that is intentional. So the save/restore sequence > > > cannot be expressed with the existing APIs. > > > > > > In v2 I tried to fix this by making pci_enable_link_state*() symmetric > > > with the disable APIs, but as pointed out during review, that also ends > > > up overriding the init-time blacklist for every caller (including VMD), > > > which is not something we want. So instead, this version adds a separate > > > pci_force_enable_link_state() API (patch 2) that re-enables the requested > > > states unconditionally. The caller is responsible for only asking for > > > states the device actually supports, and the ath drivers do this by > > > restoring exactly what pcie_aspm_enabled() reported earlier. > > > > > > The first five patches touch the PCI core: patch 1 (from Ilpo) makes > > > pci_disable_link_state() disable ASPM unconditionally, patch 2 adds the > > > new API, patch 3 moves the D0 transition needed before enabling PCI-PM > > > L1 PM Substates (PCIe r6.0, sec 5.5.4) into the shared helper and drops > > > it from the vmd and pcie-qcom callers, patch 4 cleans up the kernel-doc, > > > and patch 5 makes pcie_aspm_enabled() return the enabled state mask so it > > > can be used for save/restore. The last three patches convert the ath > > > drivers. > > > > > > Testing > > > ======= > > > > > > I've tested this series on a Lenovo Thinkpad T14s with WCN7850 (so that's > > > just the ath12k driver). Rest of the drivers are compile tested only. > > > > > > Merging Strategy > > > ================ > > > > > > Even though there is no build dependency between the PCI core and atheros > > > patches, there is a functional dependency. So I'd recommend creating an > > > immutable branch with the PCI patches and merging that branch into both > > > the PCI and linux-wireless trees, and finally merging the atheros patches > > > into the linux-wireless tree. > > > > > > If the immutable branch seems like a hassle, then the PCI core patches > > > could get merged first and the atheros patches can wait for the next > > > cycle. > > > > > > - Mani > > > > > > Changes in v3: > > > * Dropped the change that made pci_enable_link_state*() symmetric with the > > > disable APIs. Instead added a new pci_force_enable_link_state() API used > > > only by the ath drivers, so the init-time blacklist stays overridable > > > only via pcie_aspm=force and existing callers like VMD are left > > > untouched. > > > * Fixed the locked path to use pci_set_power_state_locked() for the D0 > > > transition. The previous version called the non-locked variant, which > > > re-acquires pci_bus_sem. > > > * ath drivers now disable PCIE_LINK_STATE_ASPM_ALL instead of > > > PCIE_LINK_STATE_ALL so that CLKPM is preserved and can be restored > > > (pcie_aspm_enabled() doesn't report CLKPM). > > > * Reworked the kernel-doc patch to cover both the enable and disable APIs > > > and reference the new API. > > > * Rebased on top of v7.2-rc1. > > > > > > Changes in v2: > > > * Reworked the pcie_aspm_enabled() API to return the enabled states > > > instead of bool and used it to save/restore the ASPM states in ath > > > drivers. > > > * Added a patch from Ilpo to disable ASPM even if BIOS didn't grant > > > permission. > > > * Added the CONFIG_PCIEASPM dependency to ath{10/11/12}k drivers. > > > * Rebased on top of v6.17-rc1. > > > > > > Signed-off-by: Manivannan Sadhasivam > > > --- > > > Ilpo Järvinen (1): > > > PCI/ASPM: Always disable ASPM when driver requests it > > > > I put this first patch on pci/aspm for v7.4 because there seems to be > > a consensus that it's better to have the ASPM core disable things even > > if it doesn't technically have control of ASPM, because the > > alternative is that drivers just do it themselves, also ignoring ASPM > > ownership concerns. Having the drivers do it just means the PCI core > > ASPM support doesn't know what's happening. > > > > I think we should defer the rest of these because I think there's a > > little room to make the enable/disable/force-enable dance more > > intuitive for the drivers. As far as I know, the rest of the series > > is definite cleanups but doesn't fix any actual functional issues. > > > > I wouldn't just categorize the rest of the patches as mere cleanups. They are > indeed fixing an obvious race between PCI core and the driver doing ASPM dance > at the same time. Agreed. > But for sure, even after these patches, one can trigger the > same race between sysfs 'config' and the driver/PCI core, but that's more of an > user trying to perform an action to trigger a race vs race happening within the > kernel without user intervention (which is too bad). Which is why I suggested moving to a counter based approach so we could arbitrarily overlap any number of disable/enable pairs for a state in arbitrary order, no matter what's the source. > I'd really like to see a way forward for these patches, even with a new API and > not let them fall through the cracks. Me too. The needs have simply outgrown the old API (which was never good anyway due to its asymmetry caveat). -- i.