Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760453AbYLVWMl (ORCPT ); Mon, 22 Dec 2008 17:12:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760192AbYLVWLS (ORCPT ); Mon, 22 Dec 2008 17:11:18 -0500 Received: from g4t0014.houston.hp.com ([15.201.24.17]:45753 "EHLO g4t0014.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758850AbYLVWLQ (ORCPT ); Mon, 22 Dec 2008 17:11:16 -0500 From: Andrew Patterson Subject: [PATCH] ASPM: Use msleep instead of cpu_relax during link retraining To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Cc: andrew.patterson@hp.com, matthew@wil.cx, shaohua.li@intel.com Date: Mon, 22 Dec 2008 15:11:57 -0700 Message-ID: <20081222221156.29645.95982.stgit@bluto> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2026 Lines: 62 ASPM: Use msleep instead of cpu_relax during link retraining The cpu_relax() function can be a noop on certain architectures like IA-64 when CPU threads are disabled, so use msleep instead during link retraining busy/wait loop. Introduce define LINK_RETRAIN_TIMEOUT instead of hard-coding timeout in pcie_aspm_configure_common_clock. Signed-off-by: Andrew Patterson --- diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index e361c7d..c00fd65 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include "../pci.h" @@ -70,6 +71,8 @@ static const char *policy_str[] = { [POLICY_POWERSAVE] = "powersave" }; +#define LINK_RETRAIN_TIMEOUT HZ + static int policy_to_aspm_state(struct pci_dev *pdev) { struct pcie_link_state *link_state = pdev->link_state; @@ -217,16 +220,18 @@ static void pcie_aspm_configure_common_clock(struct pci_dev *pdev) pci_write_config_word(pdev, pos + PCI_EXP_LNKCTL, reg16); /* Wait for link training end */ - /* break out after waiting for 1 second */ + /* break out after waiting for timeout */ start_jiffies = jiffies; - while ((jiffies - start_jiffies) < HZ) { + for (;;) { pci_read_config_word(pdev, pos + PCI_EXP_LNKSTA, ®16); if (!(reg16 & PCI_EXP_LNKSTA_LT)) break; - cpu_relax(); + if ((jiffies - start_jiffies) >= LINK_RETRAIN_TIMEOUT) + break; + msleep(1); } /* training failed -> recover */ - if ((jiffies - start_jiffies) >= HZ) { + if ((jiffies - start_jiffies) >= LINK_RETRAIN_TIMEOUT) { dev_printk (KERN_ERR, &pdev->dev, "ASPM: Could not configure" " common clock\n"); i = 0; -- 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/