Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964792AbZJIWKg (ORCPT ); Fri, 9 Oct 2009 18:10:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934539AbZJIWKg (ORCPT ); Fri, 9 Oct 2009 18:10:36 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:50476 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934517AbZJIWKe (ORCPT ); Fri, 9 Oct 2009 18:10:34 -0400 From: "Rafael J. Wysocki" To: Bjorn Helgaas Subject: Re: [RFC][PATCH 1/4] PCI PM: Add function for checking PME status of devices Date: Sat, 10 Oct 2009 00:11:28 +0200 User-Agent: KMail/1.12.1 (Linux/2.6.32-rc3-rjw; KDE/4.3.1; x86_64; ; ) Cc: Linux PCI , pm list , Jesse Barnes , Matthew Garrett , ACPI Devel Maling List , LKML , Alan Stern , Shaohua Li References: <200910090051.50932.rjw@sisk.pl> <200910090052.48493.rjw@sisk.pl> <200910081732.03157.bjorn.helgaas@hp.com> In-Reply-To: <200910081732.03157.bjorn.helgaas@hp.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200910100011.28268.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3583 Lines: 96 On Friday 09 October 2009, Bjorn Helgaas wrote: > On Thursday 08 October 2009 04:52:48 pm Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki > > > > Add function pci_check_pme_status() that will check the PME status > > bit of given device and clear it along with the PME enable bit. It > > will be necessary for PCI run-time power management. > > > > Based on a patch from Shaohua Li > > > > Signed-off-by: Rafael J. Wysocki > > --- > > drivers/pci/pci.c | 35 +++++++++++++++++++++++++++++++++++ > > drivers/pci/pci.h | 1 + > > 2 files changed, 36 insertions(+) > > > > Index: linux-2.6/drivers/pci/pci.h > > =================================================================== > > --- linux-2.6.orig/drivers/pci/pci.h > > +++ linux-2.6/drivers/pci/pci.h > > @@ -49,6 +49,7 @@ struct pci_platform_pm_ops { > > extern int pci_set_platform_pm(struct pci_platform_pm_ops *ops); > > extern void pci_update_current_state(struct pci_dev *dev, pci_power_t state); > > extern void pci_disable_enabled_device(struct pci_dev *dev); > > +extern bool pci_check_pme_status(struct pci_dev *dev); > > extern void pci_pm_init(struct pci_dev *dev); > > extern void platform_pci_wakeup_init(struct pci_dev *dev); > > extern void pci_allocate_cap_save_buffers(struct pci_dev *dev); > > Index: linux-2.6/drivers/pci/pci.c > > =================================================================== > > --- linux-2.6.orig/drivers/pci/pci.c > > +++ linux-2.6/drivers/pci/pci.c > > @@ -1167,6 +1167,41 @@ int pci_set_pcie_reset_state(struct pci_ > > } > > > > /** > > + * pci_check_pme_status - Check if given device has generated PME. > > + * @dev: Device to check. > > + * > > + * Check the PME status of the device, clear PME status and PME enable. Return > > + * 'true' if PME has been generated by the device (and hasn't been spurious) or > > + * 'false' otherwise. > > This comment confuses me because it implies that we always clear PME enable, > but that's not what the code does. If PME_STATUS is not asserted, the code > doesn't write anything. Well, that's a shortcut, perhaps going too far. It should say "clear PME status and PME enable, if the PME status was set". Will fix. > > + */ > > +bool pci_check_pme_status(struct pci_dev *dev) > > +{ > > + int pmcsr_pos; > > + u16 pmcsr; > > + bool ret = false; > > + > > + if (!dev->pm_cap) > > + return false; > > + > > + pmcsr_pos = dev->pm_cap + PCI_PM_CTRL; > > + /* clear PME status and disable PME to avoid interrupt flood */ > > + pci_read_config_word(dev, pmcsr_pos, &pmcsr); > > + if (!(pmcsr & PCI_PM_CTRL_PME_STATUS)) > > + return false; > > + > > + pmcsr |= PCI_PM_CTRL_PME_STATUS; > > + /* Ignore spurious PME or clear PME enable if it's not spurious. */ > > + if (pmcsr & PCI_PM_CTRL_PME_ENABLE) { > > + pmcsr &= ~PCI_PM_CTRL_PME_ENABLE; > > + ret = true; > > + } > > + > > + pci_write_config_word(dev, pmcsr_pos, pmcsr); > > I can't tell whether the comment or the code is what was intended, The code. I'll fix the comment. > but I think the following would be a clearer way to implement the > comment: > > pci_read_config_word(..., &pmcsr); > pci_write_config_word(..., (pmcsr | STATUS) & ~ENABLE); > > if ((pmcsr & ENABLE) && (pmcsr & STATUS)) > return true; > return false; Thanks, Rafael -- 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/