From patchwork Sun Apr 15 18:47:50 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 152683 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id E39F3B6FE9 for ; Mon, 16 Apr 2012 04:43:45 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750739Ab2DOSnT (ORCPT ); Sun, 15 Apr 2012 14:43:19 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:44130 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750699Ab2DOSnS (ORCPT ); Sun, 15 Apr 2012 14:43:18 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by ogre.sisk.pl (Postfix) with ESMTP id 37EBC1D2CE6; Sun, 15 Apr 2012 20:09:47 +0200 (CEST) Received: from ogre.sisk.pl ([127.0.0.1]) by localhost (ogre.sisk.pl [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 17160-05; Sun, 15 Apr 2012 20:09:37 +0200 (CEST) Received: from ferrari.rjw.lan (62-121-64-87.home.aster.pl [62.121.64.87]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ogre.sisk.pl (Postfix) with ESMTP id 08F651D2CB1; Sun, 15 Apr 2012 20:09:37 +0200 (CEST) From: "Rafael J. Wysocki" To: Linus Torvalds Subject: Re: [PATCH] PCI: Fix regression in pci_restore_state() Date: Sun, 15 Apr 2012 20:47:50 +0200 User-Agent: KMail/1.13.6 (Linux/3.4.0-rc2+; KDE/4.6.0; x86_64; ; ) Cc: Bjorn Helgaas , Mikko Vinni , "linux-input@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Dmitry Torokhov , Allen Kay , Jesse Barnes , "linux-pci@vger.kernel.org" References: <1334310754.17013.YahooMailNeo@web161804.mail.bf1.yahoo.com> <201204152032.36770.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Message-Id: <201204152047.51019.rjw@sisk.pl> X-Virus-Scanned: amavisd-new at ogre.sisk.pl using MkS_Vir for Linux Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Sunday, April 15, 2012, Linus Torvalds wrote: > On Sun, Apr 15, 2012 at 11:32 AM, Rafael J. Wysocki wrote: > > > > To fix the regression, make pci_restore_state() only retry the > > writes for BAR registers and only wait if the first read from > > the register doesn't return the written value. Additionally, make > > it use msleep() instead of mdelay() for waiting. > > WHAT? > > msleep() is the one that can sleep. So that part of the change is just > crazy. There's no way you can sleep during PCI register restore. OK, point taken. mdelay(10) doesn't really look good either to me in this case, though. --- From: Rafael J. Wysocki Subject: PCI: Fix regression in pci_restore_state(), v2 Commit 26f41062f28de65e11d3cf353e52d0be73442be1 PCI: check for pci bar restore completion and retry attempted to address problems with PCI BAR restoration on systems where FLR had not been completed before pci_restore_state() was called, but it did that in an utterly wrong way. First off, instead of retrying the writes for the BAR registers only, it did that for all of the PCI config space of the device, including the status register (whose value after the write quite obviously need not be the same as the written one). Second, it added arbitrary delay to pci_restore_state() even for systems where the PCI config space restoration was successful at first attempt. All of this actually caused resume failures for some devices on the Mikko's system. To fix the regression, make pci_restore_state() only retry the writes for BAR registers and only wait if the first read from the register doesn't return the written value. Reported-by: Mikko Vinni Signed-off-by: Rafael J. Wysocki --- drivers/pci/pci.c | 50 ++++++++++++++++++++++++++++++++------------------ 1 file changed, 32 insertions(+), 18 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux/drivers/pci/pci.c =================================================================== --- linux.orig/drivers/pci/pci.c +++ linux/drivers/pci/pci.c @@ -967,16 +967,40 @@ pci_save_state(struct pci_dev *dev) return 0; } +static void pci_restore_config_space(struct pci_dev *pdev, int start, int end, + int retry) +{ + int index; + + for (index = end; index >= start; index--) { + u32 val, saved; + int offset = 4 * index; + int count = retry; + + saved = pdev->saved_config_space[index]; + pci_read_config_dword(pdev, offset, &val); + while (saved != val) { + dev_dbg(&pdev->dev, "restoring config space at offset " + "%#x (was %#x, writing %#x)\n", + offset, val, saved); + pci_write_config_dword(pdev, offset, saved); + if (count-- > 0) { + pci_read_config_dword(pdev, offset, &val); + if (saved != val) + mdelay(10); + } else { + break; + } + } + } +} + /** * pci_restore_state - Restore the saved state of a PCI device * @dev: - PCI device that we're dealing with */ void pci_restore_state(struct pci_dev *dev) { - int i; - u32 val; - int tries; - if (!dev->state_saved) return; @@ -984,24 +1008,14 @@ void pci_restore_state(struct pci_dev *d pci_restore_pcie_state(dev); pci_restore_ats_state(dev); + pci_restore_config_space(dev, 10, 15, 0); /* * The Base Address register should be programmed before the command * register(s) */ - for (i = 15; i >= 0; i--) { - pci_read_config_dword(dev, i * 4, &val); - tries = 10; - while (tries && val != dev->saved_config_space[i]) { - dev_dbg(&dev->dev, "restoring config " - "space at offset %#x (was %#x, writing %#x)\n", - i, val, (int)dev->saved_config_space[i]); - pci_write_config_dword(dev,i * 4, - dev->saved_config_space[i]); - pci_read_config_dword(dev, i * 4, &val); - mdelay(10); - tries--; - } - } + pci_restore_config_space(dev, 4, 9, 10); + pci_restore_config_space(dev, 0, 3, 0); + pci_restore_pcix_state(dev); pci_restore_msi_state(dev); pci_restore_iov_state(dev);