[PATCH] PCI: Enable ATS at the device state restore

[Hao, Xudong]

When system go to S3 or S4 sleep and then return, some register of PCI device does not be restored correctly, such as ATS capability. The same problem happen on pci reset function.

This patch enables ATS at the device state restore if PCI device has ATS capability.

Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx>
Signed-off-by: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
---
 drivers/pci/ats.c |   17 +++++++++++++++++
 drivers/pci/pci.c |    1 +
 drivers/pci/pci.h |    8 ++++++++
 3 files changed, 26 insertions(+), 0 deletions(-)
 
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 7ec56fb..a6c2b35 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -127,6 +127,23 @@ void pci_disable_ats(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_disable_ats);
 
+void pci_restore_ats_state(struct pci_dev *dev)
+{
+	u16 ctrl;
+
+	if (!pci_ats_enabled(dev))
+		return;
+	if (!pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ATS))
+		BUG();
+
+	ctrl = PCI_ATS_CTRL_ENABLE;
+	if (!dev->is_virtfn)
+		ctrl |= PCI_ATS_CTRL_STU(dev->ats->stu - PCI_ATS_MIN_STU);
+
+	pci_write_config_word(dev, dev->ats->pos + PCI_ATS_CTRL, ctrl);
+}
+EXPORT_SYMBOL_GPL(pci_restore_ats_state);
+
 /**
  * pci_ats_queue_depth - query the ATS Invalidate Queue Depth
  * @dev: the PCI device
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6f45a73..6dafc1d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -956,6 +956,7 @@ void pci_restore_state(struct pci_dev *dev)
 
 	/* PCI Express register must be restored first */
 	pci_restore_pcie_state(dev);
+	pci_restore_ats_state(dev);
 
 	/*
 	 * The Base Address register should be programmed before the command
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index b74084e..a4f3140 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -249,6 +249,14 @@ struct pci_sriov {
 	u8 __iomem *mstate;	/* VF Migration State Array */
 };
 
+#ifdef CONFIG_PCI_ATS
+extern void pci_restore_ats_state(struct pci_dev *dev);
+#else
+static inline void pci_restore_ats_state(struct pci_dev *dev)
+{
+}
+#endif /* CONFIG_PCI_ATS */
+
 #ifdef CONFIG_PCI_IOV
 extern int pci_iov_init(struct pci_dev *dev);
 extern void pci_iov_release(struct pci_dev *dev);
--
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