PCI PM: Introduce __pci_[start|complete]_power_transition() (rev. 2)

The radeonfb driver needs to program the device's PMCSR directly due
to some quirky hardware it has to handle (see
http://bugzilla.kernel.org/show_bug.cgi?id=12846 for details) and
after doing that it needs to call the platform (usually ACPI) to
finish the power transition of the device.  Currently it uses
pci_set_power_state() for this purpose, however making a specific
assumption about the internal behavior of this function, which has
changed recently so that this assumption is no longer satisfied.
For this reason, introduce __pci_complete_power_transition() that may
be called by the radeonfb driver to complete the power transition of
the device.  For symmetry, introduce __pci_start_power_transition().

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 52 insertions, 18 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 979ceb1d37e8..de54fd643baf 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -540,6 +540,53 @@ void pci_update_current_state(struct pci_dev *dev, pci_power_t state)
 }
 
 /**
+ * pci_platform_power_transition - Use platform to change device power state
+ * @dev: PCI device to handle.
+ * @state: State to put the device into.
+ */
+static int pci_platform_power_transition(struct pci_dev *dev, pci_power_t state)
+{
+        int error;
+
+        if (platform_pci_power_manageable(dev)) {
+                error = platform_pci_set_power_state(dev, state);
+                if (!error)
+                        pci_update_current_state(dev, state);
+        } else {
+                error = -ENODEV;
+                /* Fall back to PCI_D0 if native PM is not supported */
+                pci_update_current_state(dev, PCI_D0);
+        }
+
+        return error;
+}
+
+/**
+ * __pci_start_power_transition - Start power transition of a PCI device
+ * @dev: PCI device to handle.
+ * @state: State to put the device into.
+ */
+static void __pci_start_power_transition(struct pci_dev *dev, pci_power_t state)
+{
+        if (state == PCI_D0)
+                pci_platform_power_transition(dev, PCI_D0);
+}
+
+/**
+ * __pci_complete_power_transition - Complete power transition of a PCI device
+ * @dev: PCI device to handle.
+ * @state: State to put the device into.
+ *
+ * This function should not be called directly by device drivers.
+ */
+int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state)
+{
+        return state > PCI_D0 ?
+                        pci_platform_power_transition(dev, state) : -EINVAL;
+}
+EXPORT_SYMBOL_GPL(__pci_complete_power_transition);
+
+/**
  * pci_set_power_state - Set the power state of a PCI device
  * @dev: PCI device to handle.
  * @state: PCI power state (D0, D1, D2, D3hot) to put the device into.
@@ -575,16 +622,8 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
         if (dev->current_state == state)
                 return 0;
 
-        if (state == PCI_D0) {
-                /*
-                 * Allow the platform to change the state, for example via ACPI
-                 * _PR0, _PS0 and some such, but do not trust it.
-                 */
-                int ret = platform_pci_power_manageable(dev) ?
-                        platform_pci_set_power_state(dev, PCI_D0) : 0;
-                if (!ret)
-                        pci_update_current_state(dev, PCI_D0);
-        }
+        __pci_start_power_transition(dev, state);
+
         /* This device is quirked not to be put into D3, so
            don't put it in D3 */
         if (state == PCI_D3hot && (dev->dev_flags & PCI_DEV_FLAGS_NO_D3))
@@ -592,14 +631,8 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
 
         error = pci_raw_set_power_state(dev, state);
 
-        if (state > PCI_D0 && platform_pci_power_manageable(dev)) {
-                /* Allow the platform to finalize the transition */
-                int ret = platform_pci_set_power_state(dev, state);
-                if (!ret) {
-                        pci_update_current_state(dev, state);
-                        error = 0;
-                }
-        }
+        if (!__pci_complete_power_transition(dev, state))
+                error = 0;
 
         return error;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 7bd624bfdcfd..df3644132617 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -689,6 +689,7 @@ size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size);
 /* Power management related routines */
 int pci_save_state(struct pci_dev *dev);
 int pci_restore_state(struct pci_dev *dev);
+int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state);
 int pci_set_power_state(struct pci_dev *dev, pci_power_t state);
 pci_power_t pci_choose_state(struct pci_dev *dev, pm_message_t state);
 bool pci_pme_capable(struct pci_dev *dev, pci_power_t state);