Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965172Ab3DQQLU (ORCPT ); Wed, 17 Apr 2013 12:11:20 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:35599 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752070Ab3DQQLT (ORCPT ); Wed, 17 Apr 2013 12:11:19 -0400 From: "Rafael J. Wysocki" To: Bjorn Helgaas Cc: Yinghai Lu , LKML , Linux PM list , Linux PCI , "Benenati, Chris J" , Ajaykumar Hotchandani Subject: Re: [PATCH] PCI / PM: Fix fallback to PCI_D0 in pci_platform_power_transition() Date: Wed, 17 Apr 2013 18:19:12 +0200 Message-ID: <5921138.PXoHfspviV@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.9.0-rc6+; KDE/4.9.5; x86_64; ; ) In-Reply-To: References: <48795235.crcTAaJqPb@vostro.rjw.lan> <2880576.TkeK8oBDas@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4967 Lines: 114 On Tuesday, April 16, 2013 12:31:55 PM Bjorn Helgaas wrote: > On Tue, Apr 16, 2013 at 12:01 PM, Rafael J. Wysocki wrote: > > On Monday, April 15, 2013 02:18:18 PM Bjorn Helgaas wrote: > >> On Fri, Apr 12, 2013 at 11:50 PM, Yinghai Lu wrote: > >> > On Fri, Apr 12, 2013 at 4:58 PM, Rafael J. Wysocki wrote: > >> >> From: Rafael J. Wysocki > >> >> > >> >> Commit b51306c (PCI: Set device power state to PCI_D0 for device > >> >> without native PM support) modified pci_platform_power_transition() > >> >> by adding code causing dev->current_state for devices that don't > >> >> support native PCI PM but are power-manageable by the platform to be > >> >> changed to PCI_D0 regardless of the value returned by the preceding > >> >> platform_pci_set_power_state(). In particular, that also is done > >> >> if the platform_pci_set_power_state() has been successful, which > >> >> causes the correct power state of the device set by > >> >> pci_update_current_state() in that case to be overwritten by PCI_D0. > >> >> > >> >> Fix that mistake by making the fallback to PCI_D0 only happen if > >> >> the platform_pci_set_power_state() has returned an error. > >> >> > >> >> Reported-by: Chris J. Benenati > >> >> Signed-off-by: Rafael J. Wysocki > >> >> Cc: > >> > >> I folded in Yinghai's simplification and added a URL to Chris's report > >> and applied to my pci/rafael-pm branch: > >> http://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/log/?h=pci/rafael-pm > >> > >> If it still looks good to you, Rafael, I'll merge it to next for v3.10. > > > > Well, the simplification adds an extra check for error into both code paths, > > so I'm not sure if it's really worth it (that's why I didn't do it originally > > in the first place), but I suppose that's not a big deal. It looks good as far > > as the correctness is concerned anyway. > > > >> I don't know what the user-visible effect of this is, and it's been > >> around for a long time, but if you think this should go in v3.9 > >> instead, let me know. > > > > I think v3.9+stable should be sufficient. > > It sounds like you meant to say "v3.10+stable should be sufficient". > Is that right, or do you want me to push this to Linus before v3.9 is > released? Yes, I meant v3.10+stable. Sorry. Thanks, Rafael > >> >> --- > >> >> drivers/pci/pci.c | 3 +-- > >> >> 1 file changed, 1 insertion(+), 2 deletions(-) > >> >> > >> >> Index: linux-pm/drivers/pci/pci.c > >> >> =================================================================== > >> >> --- linux-pm.orig/drivers/pci/pci.c > >> >> +++ linux-pm/drivers/pci/pci.c > >> >> @@ -646,8 +646,7 @@ static int pci_platform_power_transition > >> >> error = platform_pci_set_power_state(dev, state); > >> >> if (!error) > >> >> pci_update_current_state(dev, state); > >> >> - /* Fall back to PCI_D0 if native PM is not supported */ > >> >> - if (!dev->pm_cap) > >> >> + else if (!dev->pm_cap) /* Fall back to PCI_D0 */ > >> >> dev->current_state = PCI_D0; > >> >> } else { > >> >> error = -ENODEV; > >> >> > >> > > >> > Acked-by: Yinghai Lu > >> > > >> > also could simplify it further. > >> > > >> > --- > >> > drivers/pci/pci.c | 12 ++++-------- > >> > 1 file changed, 4 insertions(+), 8 deletions(-) > >> > > >> > Index: linux-2.6/drivers/pci/pci.c > >> > =================================================================== > >> > --- linux-2.6.orig/drivers/pci/pci.c > >> > +++ linux-2.6/drivers/pci/pci.c > >> > @@ -646,15 +646,11 @@ static int pci_platform_power_transition > >> > error = platform_pci_set_power_state(dev, state); > >> > if (!error) > >> > pci_update_current_state(dev, state); > >> > - /* Fall back to PCI_D0 if native PM is not supported */ > >> > - if (!dev->pm_cap) > >> > - dev->current_state = PCI_D0; > >> > - } else { > >> > + } else > >> > error = -ENODEV; > >> > - /* Fall back to PCI_D0 if native PM is not supported */ > >> > - if (!dev->pm_cap) > >> > - dev->current_state = PCI_D0; > >> > - } > >> > + > >> > + if (error && !dev->pm_cap) /* Fall back to PCI_D0 */ > >> > + dev->current_state = PCI_D0; > >> > > >> > return error; > >> > } > > -- > > I speak only for myself. > > Rafael J. Wysocki, Intel Open Source Technology Center. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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/