linux-kernel - [PATCH v4 7/9] pci: Wake-up devices before save for reset

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Message-ID: <20130805193746.9260.8439.stgit@bling.home>
Date:	Mon, 05 Aug 2013 13:37:47 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	bhelgaas@...gle.com, linux-pci@...r.kernel.org
Cc:	ddutile@...hat.com, indou.takao@...fujitsu.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 7/9] pci: Wake-up devices before save for reset

Devices come out of reset in D0.  Restoring a device to a different
post-reset state takes more smarts than our simple config space
restore, which can leave devices in an inconsistent state.  For
example, if a device is reset in D3, but the restore doesn't
successfully return the device to D3, then the actual state of the
device and dev->current_state are contradictory.  Put everything
in D0 going into the reset, then we don't need to do anything
special on the way out.

Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---
 drivers/pci/pci.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1dba7dd..b204206 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3332,6 +3332,13 @@ static void pci_dev_unlock(struct pci_dev *dev)
 
 static void pci_dev_save_and_disable(struct pci_dev *dev)
 {
+	/*
+	 * Wake-up device prior to save.  PM registers default to D0 after
+	 * reset and a simple register restore doesn't reliably return
+	 * to a non-D0 state anyway.
+	 */
+	pci_set_power_state(dev, PCI_D0);
+
 	pci_save_state(dev);
 	/*
 	 * Disable the device by clearing the Command register, except for

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