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From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: bhelgaas@google.com, rafael.j.wysocki@intel.com
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	Kai-Heng Feng <kai.heng.feng@canonical.com>
Subject: [PATCH] PCI / PM: Don't runtime suspend when device only supports wakeup from D0
Date: Wed, 22 May 2019 00:31:04 +0800	[thread overview]
Message-ID: <20190521163104.15759-1-kai.heng.feng@canonical.com> (raw)

There's an xHC device that doesn't wake when a USB device gets plugged
to its USB port. The driver's own runtime suspend callback was called,
PME signaling was enabled, but it stays at PCI D0.

A PCI device can be runtime suspended to D0 when it supports D0 PME and
its _S0W reports D0. Theoratically this should work, but as [1]
specifies, D0 doesn't have wakeup capability.

To avoid this problematic situation, we should avoid runtime suspend if
D0 is the only state that can wake up the device.

[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/kernel/device-working-state-d0

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/pci/pci-driver.c | 5 +++++
 drivers/pci/pci.c        | 2 +-
 include/linux/pci.h      | 3 +++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index cae630fe6387..15a6310c5d7b 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -1251,6 +1251,11 @@ static int pci_pm_runtime_suspend(struct device *dev)
 		return 0;
 	}
 
+	if (pci_target_state(pci_dev, device_can_wakeup(dev)) == PCI_D0) {
+		dev_dbg(dev, "D0 doesn't have wakeup capability\n");
+		return -EBUSY;
+	}
+
 	pci_dev->state_saved = false;
 	if (pm && pm->runtime_suspend) {
 		error = pm->runtime_suspend(dev);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8abc843b1615..ceee6efbbcfe 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2294,7 +2294,7 @@ EXPORT_SYMBOL(pci_wake_from_d3);
  * If the platform can't manage @dev, return the deepest state from which it
  * can generate wake events, based on any available PME info.
  */
-static pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup)
+pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup)
 {
 	pci_power_t target_state = PCI_D3hot;
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 4a5a84d7bdd4..91e8dc4d04aa 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1188,6 +1188,7 @@ bool pci_pme_capable(struct pci_dev *dev, pci_power_t state);
 void pci_pme_active(struct pci_dev *dev, bool enable);
 int pci_enable_wake(struct pci_dev *dev, pci_power_t state, bool enable);
 int pci_wake_from_d3(struct pci_dev *dev, bool enable);
+pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup);
 int pci_prepare_to_sleep(struct pci_dev *dev);
 int pci_back_from_sleep(struct pci_dev *dev);
 bool pci_dev_run_wake(struct pci_dev *dev);
@@ -1672,6 +1673,8 @@ static inline int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
 { return 0; }
 static inline int pci_wake_from_d3(struct pci_dev *dev, bool enable)
 { return 0; }
+pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup)
+{ return PCI_D0; }
 static inline pci_power_t pci_choose_state(struct pci_dev *dev,
 					   pm_message_t state)
 { return PCI_D0; }
-- 
2.17.1


             reply	other threads:[~2019-05-21 16:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-21 16:31 Kai-Heng Feng [this message]
2019-05-21 22:23 ` Bjorn Helgaas
2019-05-22  3:42   ` Kai Heng Feng
2019-05-22 13:48     ` Bjorn Helgaas
2019-05-22 15:46       ` Kai Heng Feng
2019-05-22 18:11         ` Bjorn Helgaas
2019-05-22 18:39           ` Alan Stern
2019-05-22 18:53             ` Lukas Wunner
2019-05-22 19:05               ` Kai Heng Feng
2019-05-22 20:52             ` Bjorn Helgaas
2019-05-23  4:39               ` Kai-Heng Feng
2019-05-27 16:57                 ` Bjorn Helgaas
2019-06-05 11:57                   ` Bjorn Helgaas
2019-07-05  7:02                     ` Kai-Heng Feng
2019-07-05  9:39                       ` Rafael J. Wysocki
2019-07-05 13:51                         ` Kai-Heng Feng
2019-07-09 13:45                       ` Bjorn Helgaas
2019-09-02 13:47                         ` Kai-Heng Feng

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