On Wed, Jul 16, 2014 at 03:33:42PM +0530, Vidya Sagar wrote:
> From: Vidya Sagar <sagar.tv@xxxxxxxxx>
>
> Commit 1a680b7c3258 ("PCI: PCIe links may not get configured for ASPM
> under POWERSAVE mode") moved pcie_aspm_powersave_config_link() out of
> pci_raw_set_power_state() to pci_set_power_state() which would enable
> ASPM. But, with Commit db288c9c5f9d ("PCI / PM: restore the original
> behavior of pci_set_power_state()"), which re-introduced the following check
> ./drivers/pci/pci.c: pci_set_power_state()
>
> + /* Check if we're already there */
> + if (dev->current_state == state)
> + return 0;
>
> in pci_set_power_state(), call to pcie_aspm_powersave_config_link() is never
> made leaving ASPM broken.
> Fix it by configuring links for ASPM in do_pci_enable_device() instead of
> pci_set_power_state()
>
> Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Signed-off-by: Vidya Sagar <sagar.tv@xxxxxxxxx>
I applied this to pci/misc for v3.17 with the following changelog:
It would still make me feel better if Matthew and/or Rafael acked this.
PCI: Configure ASPM when enabling device
We can't do ASPM configuration at enumeration-time because enabling it
makes some defective hardware unresponsive, even if ASPM is disabled later
(see 41cd766b0659 ("PCI: Don't enable aspm before drivers have had a chance
to veto it"). Therefore, we have to do it after a driver claims the
device.
We previously configured ASPM in pci_set_power_state(), but that's not a
very good place because it's not really related to setting the PCI device
power state, and doing it there means:
- We incorrectly skipped ASPM config when setting a device that's
already in D0 to D0.
- We unnecessarily configured ASPM when setting a device to a low-power
state (the ASPM feature only applies when the device is in D0).
- We unnecessarily configured ASPM when called from a .resume() method
(ASPM configuration needs to be restored during resume, but I think
pci_restore_pcie_state() should already do this).
Move ASPM configuration from pci_set_power_state() to
do_pci_enable_device() so we do it when a driver enables a device.
[bhelgaas: changelog]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=79621
It would still make me feel better if Matthew and/or Rafael chimed in to
make sure this is sane.
Bjorn
> ---
> v3:
> * Modified commit message
> removed single quotes around commit messages
> added Suggested-by line
>
> v2:
> * Calling ASPM config code is moved from pci_set_power_state() to
> * do_pci_enable_device()
>
> drivers/pci/pci.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 1c8592b..81d49d3 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -839,12 +839,6 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
>
> if (!__pci_complete_power_transition(dev, state))
> error = 0;
> - /*
> - * When aspm_policy is "powersave" this call ensures
> - * that ASPM is configured.
> - */
> - if (!error && dev->bus->self)
> - pcie_aspm_powersave_config_link(dev->bus->self);
>
> return error;
> }
> @@ -1195,12 +1189,18 @@ int __weak pcibios_enable_device(struct pci_dev *dev, int bars)
> static int do_pci_enable_device(struct pci_dev *dev, int bars)
> {
> int err;
> + struct pci_dev *bridge;
> u16 cmd;
> u8 pin;
>
> err = pci_set_power_state(dev, PCI_D0);
> if (err < 0 && err != -EIO)
> return err;
> +
> + bridge = pci_upstream_bridge(dev);
> + if (bridge)
> + pcie_aspm_powersave_config_link(bridge);
> +
> err = pcibios_enable_device(dev, bars);
> if (err < 0)
> return err;
> --
> 1.8.1.5
>
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