linux-kernel - [PATCH] PCI: Remove not needed check in disable aspm link

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Date:	Mon, 18 Mar 2013 10:37:06 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	stable@...nel.org
Subject: [PATCH] PCI: Remove not needed check in disable aspm link

Roman reported ath5k does not work anymore on 3.8.
Bisected to
| commit 8c33f51df406e1a1f7fa4e9b244845b7ebd61fa6
| Author: Taku Izumi <izumi.taku@...fujitsu.com>
| Date:   Tue Oct 30 15:27:13 2012 +0900
|
|    PCI/ACPI: Request _OSC control before scanning PCI root bus
|
|    This patch moves up the code block to request _OSC control in order to
|    separate ACPI work and PCI work in acpi_pci_root_add().

It make pci_disable_link_state does not work anymore as acpi_disabled
is set before pci root bus scanning.
It will skip that in quirks and pcie_aspm_sanity_check.

We could revert to old logic, but that will make booting path and hotplug
path with different aspm_disabled again.

Acctually we don't need to check aspm_disabled in disable link, as
we already have protection about link state following.

https://bugzilla.kernel.org/show_bug.cgi?id=55211
http://article.gmane.org/gmane.linux.kernel.pci/20640

Need it for 3.8 stable.

Reported-by: Roman Yepishev <roman.yepishev@...il.com>
Bisected-by: Roman Yepishev <roman.yepishev@...il.com>
Tested-by: Roman Yepishev <roman.yepishev@...il.com>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Cc: Taku Izumi <izumi.taku@...fujitsu.com>
Cc: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc: stable@...nel.org

---
 drivers/pci/pcie/aspm.c |   21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

Index: linux-2.6/drivers/pci/pcie/aspm.c
===================================================================
--- linux-2.6.orig/drivers/pci/pcie/aspm.c
+++ linux-2.6/drivers/pci/pcie/aspm.c
@@ -493,15 +493,6 @@ static int pcie_aspm_sanity_check(struct
 			return -EINVAL;
 
 		/*
-		 * If ASPM is disabled then we're not going to change
-		 * the BIOS state. It's safe to continue even if it's a
-		 * pre-1.1 device
-		 */
-
-		if (aspm_disabled)
-			continue;
-
-		/*
 		 * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
 		 * RBER bit to determine if a function is 1.1 version device
 		 */
@@ -718,15 +709,11 @@ void pcie_aspm_powersave_config_link(str
  * pci_disable_link_state - disable pci device's link state, so the link will
  * never enter specific states
  */
-static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem,
-				     bool force)
+static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
 {
 	struct pci_dev *parent = pdev->bus->self;
 	struct pcie_link_state *link;
 
-	if (aspm_disabled && !force)
-		return;
-
 	if (!pci_is_pcie(pdev))
 		return;
 
@@ -757,13 +744,13 @@ static void __pci_disable_link_state(str
 
 void pci_disable_link_state_locked(struct pci_dev *pdev, int state)
 {
-	__pci_disable_link_state(pdev, state, false, false);
+	__pci_disable_link_state(pdev, state, false);
 }
 EXPORT_SYMBOL(pci_disable_link_state_locked);
 
 void pci_disable_link_state(struct pci_dev *pdev, int state)
 {
-	__pci_disable_link_state(pdev, state, true, false);
+	__pci_disable_link_state(pdev, state, true);
 }
 EXPORT_SYMBOL(pci_disable_link_state);
 
@@ -781,7 +768,7 @@ void pcie_clear_aspm(struct pci_bus *bus
 		__pci_disable_link_state(child, PCIE_LINK_STATE_L0S |
 					 PCIE_LINK_STATE_L1 |
 					 PCIE_LINK_STATE_CLKPM,
-					 false, true);
+					 false);
 	}
 }
 
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