linux-kernel - [PATCH] [suspend] pci_raw_set_power_state: replace msleep by udelay in resuming procedure

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Date:	Thu, 16 Jul 2009 23:43:27 +0800
From:	Wu Zhangjin <wuzhangjin@...il.com>
To:	linux-pm@...ts.linux-foundation.org
Cc:	linux-kernel@...r.kernel.org, len.brown@...el.com, pavel@....cz,
	zhangfx@...ote.com, wuzj@...ote.com, yanh@...ote.com,
	Wu Zhangjin <wuzhangjin@...il.com>
Subject: [PATCH] [suspend] pci_raw_set_power_state: replace msleep by udelay in resuming procedure

we can not call msleep() when resuming from STR/Standby: if the
current_state of the pci device is PCI_D3hot, means we are in the
procedure of resuming, in this procedure, we can not re-schedule,
otherwise, there will be a deadlock.

Signed-off-by: Wu Zhangjin <wuzhangjin@...il.com>
---
 drivers/pci/pci.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 440f4fb..3d9a4e2 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -497,8 +497,18 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
 
 	/* Mandatory power management transition delays */
 	/* see PCI PM 1.1 5.6.1 table 18 */
-	if (state == PCI_D3hot || dev->current_state == PCI_D3hot)
+
+	/* we can not call msleep() when resume:
+	 *
+	 *   if the current_state is PCI_D3hot, means we are in the procedure
+	 *   of resuming, in this procedure, we can not re-schedule, otherwise,
+	 *   there will be a deadlock.
+	 */
+
+	if (state == PCI_D3hot)
 		msleep(pci_pm_d3_delay);
+	else if (dev->current_state == PCI_D3hot)
+		udelay(pci_pm_d3_delay);
 	else if (state == PCI_D2 || dev->current_state == PCI_D2)
 		udelay(PCI_PM_D2_DELAY);
 
-- 
1.6.2.1

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