[PATCH] Revert 991de2e59090 ("PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()")

[Bjorn Helgaas]

991de2e59090 appeared in v4.3.  ÐÐÐÐ reported that the Elcus-1553 TA1-PCI
driver worked in v4.2 but not v4.3 and bisected it to 991de2e59090.  Sunjin
reported that the RocketRAID 272x driver worked in v4.2 but not v4.3.  In
both cases, booting with "pci=routirq" is a workaround.

I think the problem is that after 991de2e59090, we no longer call
pcibios_enable_irq() for upstream bridges.  Prior to 991de2e59090, when a
driver called pci_enable_device(), we recursively called
pcibios_enable_irq() for upstream bridges via pci_enable_bridge().

After 991de2e59090, we call pcibios_enable_irq() from pci_device_probe()
instead of the pci_enable_device() path, which does *not* call
pcibios_enable_irq() for upstream bridges.

The purpose of 991de2e59090 was to help support IOAPIC hotplug, so
reverting it likely breaks that.

Note: this also reverts 8affb487d4a4 ("x86/PCI: Don't alloc pcibios-irq
when MSI is enabled").

Link: https://bugzilla.kernel.org/show_bug.cgi?id=111211
Fixes: 991de2e59090 ("PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()")
Reported-by: ÐÐÐÐ ÐÐÑÐÐ <oleg.moroz@xxxxxxxxxxxxx>
Reported-by: Sunjin Yang <fan4326@xxxxxxxxx>
Not-yet-signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
 arch/x86/include/asm/pci_x86.h |    2 ++
 arch/x86/pci/common.c          |   27 +++++++++++----------------
 arch/x86/pci/intel_mid_pci.c   |    7 ++-----
 arch/x86/pci/irq.c             |   15 ++++++++++++++-
 drivers/acpi/pci_irq.c         |    8 ++++++++
 5 files changed, 37 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index 46873fb..d08eacd2 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -93,6 +93,8 @@ extern raw_spinlock_t pci_config_lock;
 extern int (*pcibios_enable_irq)(struct pci_dev *dev);
 extern void (*pcibios_disable_irq)(struct pci_dev *dev);
 
+extern bool mp_should_keep_irq(struct device *dev);
+
 struct pci_raw_ops {
 	int (*read)(unsigned int domain, unsigned int bus, unsigned int devfn,
 						int reg, int len, u32 *val);
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 2879efc..9df5ab9 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -711,28 +711,23 @@ int pcibios_add_device(struct pci_dev *dev)
 	return 0;
 }
 
-int pcibios_alloc_irq(struct pci_dev *dev)
+int pcibios_enable_device(struct pci_dev *dev, int mask)
 {
-	/*
-	 * If the PCI device was already claimed by core code and has
-	 * MSI enabled, probing of the pcibios IRQ will overwrite
-	 * dev->irq.  So bail out if MSI is already enabled.
-	 */
-	if (pci_dev_msi_enabled(dev))
-		return -EBUSY;
+	int err;
 
-	return pcibios_enable_irq(dev);
-}
+	if ((err = pci_enable_resources(dev, mask)) < 0)
+		return err;
 
-void pcibios_free_irq(struct pci_dev *dev)
-{
-	if (pcibios_disable_irq)
-		pcibios_disable_irq(dev);
+	if (!pci_dev_msi_enabled(dev))
+		return pcibios_enable_irq(dev);
+
+	return 0;
 }
 
-int pcibios_enable_device(struct pci_dev *dev, int mask)
+void pcibios_disable_device (struct pci_dev *dev)
 {
-	return pci_enable_resources(dev, mask);
+	if (!pci_dev_msi_enabled(dev) && pcibios_disable_irq)
+		pcibios_disable_irq(dev);
 }
 
 int pci_ext_cfg_avail(void)
diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c
index 0d24e7c..354180e 100644
--- a/arch/x86/pci/intel_mid_pci.c
+++ b/arch/x86/pci/intel_mid_pci.c
@@ -256,13 +256,10 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev)
 
 static void intel_mid_pci_irq_disable(struct pci_dev *dev)
 {
-	if (pci_has_managed_irq(dev)) {
+	if (!mp_should_keep_irq(&dev->dev) && dev->irq_managed &&
+	    dev->irq > 0) {
 		mp_unmap_irq(dev->irq);
 		dev->irq_managed = 0;
-		/*
-		 * Don't reset dev->irq here, otherwise
-		 * intel_mid_pci_irq_enable() will fail on next call.
-		 */
 	}
 }
 
diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index 32e7034..6c96cd3 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -1256,9 +1256,22 @@ static int pirq_enable_irq(struct pci_dev *dev)
 	return 0;
 }
 
+bool mp_should_keep_irq(struct device *dev)
+{
+	if (dev->power.is_prepared)
+		return true;
+#ifdef CONFIG_PM
+	if (dev->power.runtime_status == RPM_SUSPENDING)
+		return true;
+#endif
+
+	return false;
+}
+
 static void pirq_disable_irq(struct pci_dev *dev)
 {
-	if (io_apic_assign_pci_irqs && pci_has_managed_irq(dev)) {
+	if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) &&
+	    dev->irq_managed && dev->irq) {
 		mp_unmap_irq(dev->irq);
 		pci_reset_managed_irq(dev);
 	}
diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index d30184c..20bce3a 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -477,6 +477,14 @@ void acpi_pci_irq_disable(struct pci_dev *dev)
 	if (!pin || !pci_has_managed_irq(dev))
 		return;
 
+	/* Keep IOAPIC pin configuration when suspending */
+	if (dev->dev.power.is_prepared)
+		return;
+#ifdef CONFIG_PM
+	if (dev->dev.power.runtime_status == RPM_SUSPENDING)
+		return;
+#endif
+
 	entry = acpi_pci_irq_lookup(dev, pin);
 	if (!entry)
 		return;