Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751607AbaGPUeq (ORCPT ); Wed, 16 Jul 2014 16:34:46 -0400 Received: from mail-wg0-f45.google.com ([74.125.82.45]:37129 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998AbaGPUeo (ORCPT ); Wed, 16 Jul 2014 16:34:44 -0400 MIME-Version: 1.0 In-Reply-To: <20140716193637.GA14366@google.com> References: <1405505022-7593-1-git-send-email-vidyas@nvidia.com> <20140716193637.GA14366@google.com> From: vidya sagar Date: Thu, 17 Jul 2014 02:04:23 +0530 Message-ID: Subject: Re: [PATCH v3] PCI: enable ASPM configuration in PCIE POWERSAVE mode To: Bjorn Helgaas Cc: matthew.garrett@nebula.com, rjw@rjwysocki.net, nchumbalkar@lenovo.com, thierry.reding@gmail.com, swarren@nvidia.com, linux-pci@vger.kernel.org, kthota@nvidia.com, linux-kernel@vger.kernel.org, vidyas@nvidia.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 17, 2014 at 1:06 AM, Bjorn Helgaas wrote: > On Wed, Jul 16, 2014 at 03:33:42PM +0530, Vidya Sagar wrote: >> From: Vidya Sagar >> >> 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 >> Signed-off-by: Vidya Sagar > > 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 >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/