On Wed, May 06, 2020 at 01:34:21AM +0800, Kai-Heng Feng wrote: > The TI PCIe-to-PCI bridge prevents the Intel SoC from entering power > state deeper than PC3 due to disabled ASPM, consumes lots of unnecessary > power. On Windows ASPM L1 is enabled on the device and its upstream > bridge, so it can make the Intel SoC reach PC8 or PC10 to save lots of > power. > > In short, ASPM always gets disabled on bridge-to-bridge link. > > The special case was part of first ASPM introduction patch, commit > 7d715a6c1ae5 ("PCI: add PCI Express ASPM support"). However, it didn't > explain why ASPM needs to be disabled in special bridge-to-bridge case. > > Let's remove the the special case, as PCIe spec already envisioned ASPM > on bridge-to-bridge link. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207571 > Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com>
Applied to pci/aspm for v5.8, thanks! I did keep your Reviewed-by, Mika. If the fact that this applies only to the PCIe-to-PCI/PCI-X case makes your reviewed-by invalid, just let me know and I'll drop it. > --- > v3: > - Remove the special case completely. > > v2: > - Enable ASPM on root complex <-> bridge <-> bridge, instead of using > quirk. > drivers/pci/pcie/aspm.c | 10 ---------- > 1 file changed, 10 deletions(-) > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > index 2378ed692534..b17e5ffd31b1 100644 > --- a/drivers/pci/pcie/aspm.c > +++ b/drivers/pci/pcie/aspm.c > @@ -628,16 +628,6 @@ static void pcie_aspm_cap_init(struct pcie_link_state > *link, int blacklist) > > /* Setup initial capable state. Will be updated later */ > link->aspm_capable = link->aspm_support; > - /* > - * If the downstream component has pci bridge function, don't > - * do ASPM for now. > - */ > - list_for_each_entry(child, &linkbus->devices, bus_list) { > - if (pci_pcie_type(child) == PCI_EXP_TYPE_PCI_BRIDGE) { > - link->aspm_disable = ASPM_STATE_ALL; > - break; > - } > - } > > /* Get and check endpoint acceptable latencies */ > list_for_each_entry(child, &linkbus->devices, bus_list) { > -- > 2.17.1 >