From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758228Ab1JFKj6 (ORCPT ); Thu, 6 Oct 2011 06:39:58 -0400 Received: from smtp.eu.citrix.com ([62.200.22.115]:51085 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755830Ab1JFKj4 (ORCPT ); Thu, 6 Oct 2011 06:39:56 -0400 X-IronPort-AV: E=Sophos;i="4.68,495,1312156800"; d="scan'208";a="8246546" Date: Thu, 6 Oct 2011 11:39:49 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball-desktop To: Ajaykumar Hotchandani CC: Jesse Barnes , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] PCI: Set device power state to PCI_D0 for device without native PM support In-Reply-To: <4E8C40A8.6080205@oracle.com> Message-ID: References: <4E8C40A8.6080205@oracle.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 5 Oct 2011, Ajaykumar Hotchandani wrote: > During test of one IB card with guest VM, found that, msi is not initialized properly. > > It turns out __write_msi_msg will do nothing if device current_state is not PCI_D0. > And, that pci device does not have pm_cap in guest VM. > > There is an error in setting of power state to PCI_D0 in pci_enable_device(), but error is not returned for this. > Following is code flow: > pci_enable_device() --> __pci_enable_device_flags() --> do_pci_enable_device() --> pci_set_power_state() --> __pci_start_power_transition() > We have following condition inside __pci_start_power_transition(): > if (platform_pci_power_manageable(dev)) { > error = platform_pci_set_power_state(dev, state); > if (!error) > pci_update_current_state(dev, state); > } else { > error = -ENODEV; > /* Fall back to PCI_D0 if native PM is not supported */ > if (!dev->pm_cap) > dev->current_state = PCI_D0; > } > > Here, from platform_pci_set_power_state(), acpi_pci_set_power_state() is getting called and that is failing with ENODEV because of following condition: > if (!handle || ACPI_SUCCESS(acpi_get_handle(handle, "_EJ0",&tmp))) > return -ENODEV; > > Because of that, pci_update_current_state() is not getting called. > > With this patch, if device power state can not be set via platform_pci_set_power_state and that device does not have native pm support, then PCI device power state will be set to PCI_D0. > > Signed-off-by: Ajaykumar Hotchandani > Signed-off-by: Yinghai Lu I had the same issue and sent a patch a while ago to fix it, adding current_state = PCI_D0 in acpiphp_glue.c:register_slot it is strange that this does not work for you: http://marc.info/?l=linux-kernel&m=129891002722845&w=2