On Thu, Jul 17, 2014 at 1:06 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> 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:
Thanks,
>
> 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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