linux-kernel - [PATCH v2] PCI: enable ASPM configuration in PCIE POWERSAVE mode

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Date:	Mon, 14 Jul 2014 11:34:37 +0530
From:	Vidya Sagar <sagar.tv@...il.com>
To:	bhelgaas@...gle.com, rjw@...ysocki.net, nchumbalkar@...ovo.com,
	thierry.reding@...il.com, swarren@...dia.com, kthota@...dia.com,
	linux-pci@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, vidyas@...dia.com,
	Vidya Sagar <sagar.tv@...il.com>
Subject: [PATCH v2] PCI: enable ASPM configuration in PCIE POWERSAVE mode

From: Vidya Sagar <sagar.tv@...il.com>

'commit 1a680b7c3258 ("PCI: PCIe links may not get configured for ASPM
 under POWERSAVE mode")' moved pcie_aspm_powersave_config_link() out of
pci_raw_set_power_state() to pci_set_power_state() which would enable
ASPM. But, with 'commit db288c9c5f9d ("PCI / PM: restore the original
 behavior of pci_set_power_state()")', which re-introduced the following check
./drivers/pci/pci.c: pci_set_power_state()
+   /* Check if we're already there */
+   if (dev->current_state == state)
+       return 0;
in pci_set_power_state(), call to pcie_aspm_powersave_config_link() is never
made leaving ASPM broken.
Fix it by not returning from when the above condition is true, rather, jump to
ASPM configuration code and exit from there eventually.

Signed-off-by: Vidya Sagar <sagar.tv@...il.com>
---
v2:
* Calling ASPM config code is moved from pci_set_power_state() to
* do_pci_enable_device()

 drivers/pci/pci.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 1c8592b..81d49d3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -839,12 +839,6 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
 
 	if (!__pci_complete_power_transition(dev, state))
 		error = 0;
-	/*
-	 * When aspm_policy is "powersave" this call ensures
-	 * that ASPM is configured.
-	 */
-	if (!error && dev->bus->self)
-		pcie_aspm_powersave_config_link(dev->bus->self);
 
 	return error;
 }
@@ -1195,12 +1189,18 @@ int __weak pcibios_enable_device(struct pci_dev *dev, int bars)
 static int do_pci_enable_device(struct pci_dev *dev, int bars)
 {
 	int err;
+	struct pci_dev *bridge;
 	u16 cmd;
 	u8 pin;
 
 	err = pci_set_power_state(dev, PCI_D0);
 	if (err < 0 && err != -EIO)
 		return err;
+
+	bridge = pci_upstream_bridge(dev);
+	if (bridge)
+		pcie_aspm_powersave_config_link(bridge);
+
 	err = pcibios_enable_device(dev, bars);
 	if (err < 0)
 		return err;
-- 
1.8.1.5

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