[PATCH v1 07/11] PCI/PM: Split pci_power_up()

Rafael J. Wysocki
2022-05-05T18:31:46Z

One of the two callers of pci_power_up() invokes
pci_update_current_state() and pci_restore_state() right after calling
it, in which case running the part of it happening after the mandatory
transition delays is redundant, so move that part out of it into a new
function called pci_set_full_power_state() that will be invoked from
pci_set_power_state() which is the other caller of pci_power_up().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/pci/pci.c | 41 +++++++++++++++++++++++++++++++++++------
1 file changed, 35 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/pci/pci.c
===================================================================
--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -1189,6 +1189,9 @@ static int pci_dev_wait(struct pci_dev *
/**
* pci_power_up - Put the given device into D0
* @dev: PCI device to power up
+ *
+ * On success, return 0 or 1, depending on whether or not it is necessary to
+ * restore the device's BARs subsequently (1 is returned in that case).
*/
int pci_power_up(struct pci_dev *dev)
{
@@ -1224,10 +1227,8 @@ int pci_power_up(struct pci_dev *dev)
need_restore = (state == PCI_D3hot || dev->current_state >= PCI_D3hot) &&
!(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET);

- if (state == PCI_D0) {
- dev->current_state = PCI_D0;
+ if (state == PCI_D0)
goto end;
- }

/*
* Force the entire word to 0. This doesn't affect PME_Status, disables
@@ -1241,13 +1242,41 @@ int pci_power_up(struct pci_dev *dev)
else if (state == PCI_D2)
udelay(PCI_PM_D2_DELAY);

+end:
+ dev->current_state = PCI_D0;
+ if (need_restore)
+ return 1;
+
+ return 0;
+}
+
+/**
+ * pci_set_full_power_state - Put a PCI device into D0 and update its state
+ * @dev: PCI device to power up
+ *
+ * Call pci_power_up() to put @dev into D0, read from its PCI_PM_CTRL register
+ * to confirm the state change, restore its BARs if they might be lost and
+ * reconfigure ASPM in acordance with the new power state.
+ *
+ * If pci_restore_state() is going to be called right after a power state change
+ * to D0, it is more efficient to use pci_power_up() directly instead of this
+ * function.
+ */
+static int pci_set_full_power_state(struct pci_dev *dev)
+{
+ u16 pmcsr;
+ int ret;
+
+ ret = pci_power_up(dev);
+ if (ret < 0)
+ return ret;
+
pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;
if (dev->current_state != PCI_D0)
pci_info_ratelimited(dev, "Refused to change power state from %s to D0\n",
pci_power_name(dev->current_state));

-end:
/*
* According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT
* INTERFACE SPECIFICATION, REV. 1.2", a device transitioning
@@ -1261,7 +1290,7 @@ end:
* restore at least the BARs so that the device will be
* accessible to its driver.
*/
- if (need_restore)
+ if (ret > 0)
pci_restore_bars(dev);

if (dev->bus->self)
@@ -1415,7 +1444,7 @@ int pci_set_power_state(struct pci_dev *
return 0;

if (state == PCI_D0)
- return pci_power_up(dev);
+ return pci_set_full_power_state(dev);

/*
* This device is quirked not to be put into D3, so don't put it in