From patchwork Mon Oct 13 20:13:03 2008 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: stephen hemminger X-Patchwork-Id: 4347 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by ozlabs.org (Postfix) with ESMTP id 3DA90DDF16 for ; Tue, 14 Oct 2008 08:04:16 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755726AbYJMVEG (ORCPT ); Mon, 13 Oct 2008 17:04:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755579AbYJMVEF (ORCPT ); Mon, 13 Oct 2008 17:04:05 -0400 Received: from suva.vyatta.com ([76.74.103.44]:57900 "EHLO suva.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755539AbYJMVEC (ORCPT ); Mon, 13 Oct 2008 17:04:02 -0400 Received: from suva.vyatta.com (suva [127.0.0.1]) by suva.vyatta.com (8.13.7/8.13.7) with ESMTP id m9DL3YJs010547; Mon, 13 Oct 2008 14:03:34 -0700 Received: (from shemminger@localhost) by suva.vyatta.com (8.13.7/8.13.7/Submit) id m9DL3X2K010546; Mon, 13 Oct 2008 14:03:33 -0700 Message-Id: <20081013201452.642628937@vyatta.com> References: <20081013201302.899587376@vyatta.com> User-Agent: quilt/0.46-1 Date: Mon, 13 Oct 2008 13:13:03 -0700 From: Stephen Hemminger To: David Miller , Jeff Garzik Cc: netdev@vger.kernel.org, linux-pci@vger.kernel.org Subject: [PATCH 1/9] PCI: vpd handle longer delays in access Content-Disposition: inline; filename=vpd-delay.patch Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Accessing the VPD area can take a long time. The existing VPD access code fails consistently on my hardware. There are comments in the SysKonnect vendor driver that it can take up to 13ms per word. Change the access routines to: * use a mutex rather than spinning with IRQ's disabled and lock held * have a much longer timeout * call cond_resched while spinning Signed-off-by: Stephen Hemminger Reviewed-by: Matthew Wilcox --- drivers/pci/access.c | 55 ++++++++++++++++++++++++++++++--------------------- 1 file changed, 33 insertions(+), 22 deletions(-) --- a/drivers/pci/access.c 2008-10-13 12:46:17.000000000 -0700 +++ b/drivers/pci/access.c 2008-10-13 13:03:50.000000000 -0700 @@ -133,39 +133,46 @@ PCI_USER_WRITE_CONFIG(dword, u32) struct pci_vpd_pci22 { struct pci_vpd base; - spinlock_t lock; /* controls access to hardware and the flags */ - u8 cap; + struct mutex lock; + u16 flag; bool busy; - bool flag; /* value of F bit to wait for */ + u8 cap; }; -/* Wait for last operation to complete */ +/* + * Wait for last operation to complete. + * This code has to spin since there is no other notification from the PCI + * hardware. Since the VPD is often implemented by serial attachment to an + * EEPROM, it may take many milliseconds to complete. + */ static int pci_vpd_pci22_wait(struct pci_dev *dev) { struct pci_vpd_pci22 *vpd = container_of(dev->vpd, struct pci_vpd_pci22, base); - u16 flag, status; - int wait; + unsigned long timeout = jiffies + HZ/20 + 2; + u16 status; int ret; if (!vpd->busy) return 0; - flag = vpd->flag ? PCI_VPD_ADDR_F : 0; - wait = vpd->flag ? 10 : 1000; /* read: 100 us; write: 10 ms */ for (;;) { - ret = pci_user_read_config_word(dev, - vpd->cap + PCI_VPD_ADDR, + ret = pci_user_read_config_word(dev, vpd->cap + PCI_VPD_ADDR, &status); - if (ret < 0) + if (ret) return ret; - if ((status & PCI_VPD_ADDR_F) == flag) { + + if ((status & PCI_VPD_ADDR_F) == vpd->flag) { vpd->busy = false; return 0; } - if (wait-- == 0) + + if (time_after(jiffies, timeout)) return -ETIMEDOUT; - udelay(10); + if (fatal_signal_pending(current)) + return -EINTR; + if (!cond_resched()) + udelay(10); } } @@ -175,7 +182,7 @@ static int pci_vpd_pci22_read(struct pci struct pci_vpd_pci22 *vpd = container_of(dev->vpd, struct pci_vpd_pci22, base); u32 val; - int ret; + int ret = 0; int begin, end, i; if (pos < 0 || pos > vpd->base.len || size > vpd->base.len - pos) @@ -183,7 +190,9 @@ static int pci_vpd_pci22_read(struct pci if (size == 0) return 0; - spin_lock_irq(&vpd->lock); + if (mutex_lock_killable(&vpd->lock)) + return -EINTR; + ret = pci_vpd_pci22_wait(dev); if (ret < 0) goto out; @@ -191,15 +200,16 @@ static int pci_vpd_pci22_read(struct pci pos & ~3); if (ret < 0) goto out; + vpd->busy = true; - vpd->flag = 1; + vpd->flag = PCI_VPD_ADDR_F; ret = pci_vpd_pci22_wait(dev); if (ret < 0) goto out; ret = pci_user_read_config_dword(dev, vpd->cap + PCI_VPD_DATA, &val); out: - spin_unlock_irq(&vpd->lock); + mutex_unlock(&vpd->lock); if (ret < 0) return ret; @@ -220,7 +230,7 @@ static int pci_vpd_pci22_write(struct pc struct pci_vpd_pci22 *vpd = container_of(dev->vpd, struct pci_vpd_pci22, base); u32 val; - int ret; + int ret = 0; if (pos < 0 || pos > vpd->base.len || pos & 3 || size > vpd->base.len - pos || size < 4) @@ -231,7 +241,8 @@ static int pci_vpd_pci22_write(struct pc val |= ((u8) *buf++) << 16; val |= ((u32)(u8) *buf++) << 24; - spin_lock_irq(&vpd->lock); + if (mutex_lock_killable(&vpd->lock)) + return -EINTR; ret = pci_vpd_pci22_wait(dev); if (ret < 0) goto out; @@ -247,7 +258,7 @@ static int pci_vpd_pci22_write(struct pc vpd->flag = 0; ret = pci_vpd_pci22_wait(dev); out: - spin_unlock_irq(&vpd->lock); + mutex_unlock(&vpd->lock); if (ret < 0) return ret; @@ -279,7 +290,7 @@ int pci_vpd_pci22_init(struct pci_dev *d vpd->base.len = PCI_VPD_PCI22_SIZE; vpd->base.ops = &pci_vpd_pci22_ops; - spin_lock_init(&vpd->lock); + mutex_init(&vpd->lock); vpd->cap = cap; vpd->busy = false; dev->vpd = &vpd->base;