[RFC][PATCH 1/2] PCI PM: Introduce __pci_set_power_state()
From: Rafael J. Wysocki
Date: Sun Mar 22 2009 - 17:13:55 EST
From: Rafael J. Wysocki <rjw@xxxxxxx>
The story in http://bugzilla.kernel.org/show_bug.cgi?id=12846 shows
that setting the power state of a PCI device may sometimes require
multiple attempts to program the device's PMCSR and and/or an delay
longer than the default one. For this reason, introduce
__pci_set_power_state() that will take two additional arguments, the
number of attempts to program the power state of the device to be
made and the delay after writing a new value to the device's PMCSR.
Redefine pci_set_power_state() as __pci_set_power_state() using the
default values of the new arguments.
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
drivers/pci/pci.c | 63 +++++++++++++++++++++++++++++++++++++++-------------
include/linux/pci.h | 7 ++++-
2 files changed, 54 insertions(+), 16 deletions(-)
Index: linux-2.6/drivers/pci/pci.c
===================================================================
--- linux-2.6.orig/drivers/pci/pci.c
+++ linux-2.6/drivers/pci/pci.c
@@ -426,6 +426,9 @@ static inline int platform_pci_sleep_wak
* given PCI device
* @dev: PCI device to handle.
* @state: PCI power state (D0, D1, D2, D3hot) to put the device into.
+ * @attempts: How many times to try to change the power state of the device
+ * @delay: Delay after programming the new power state, in miliseconds (0 means
+ * use default)
*
* RETURN VALUE:
* -EINVAL if the requested state is invalid.
@@ -434,9 +437,13 @@ static inline int platform_pci_sleep_wak
* 0 if device already is in the requested state.
* 0 if device's power state has been successfully changed.
*/
-static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
+static int pci_raw_set_power_state(
+ struct pci_dev *dev,
+ pci_power_t state,
+ unsigned int attempts,
+ unsigned int delay)
{
- u16 pmcsr;
+ u16 pmcsr, new_pmcsr;
bool need_restore = false;
/* Check if we're already there */
@@ -488,17 +495,36 @@ static int pci_raw_set_power_state(struc
break;
}
- /* enter specified state */
- pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, pmcsr);
+ do {
+ /* Program the requested state */
+ pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, pmcsr);
- /* Mandatory power management transition delays */
- /* see PCI PM 1.1 5.6.1 table 18 */
- if (state == PCI_D3hot || dev->current_state == PCI_D3hot)
- msleep(pci_pm_d3_delay);
- else if (state == PCI_D2 || dev->current_state == PCI_D2)
- udelay(PCI_PM_D2_DELAY);
+ /*
+ * If delay has not been specified, use mandatory PCI power
+ * management transition delays (see PCI PM 1.1 5.6.1 table 18).
+ */
+ if (delay)
+ msleep(delay);
+ else if (state == PCI_D3hot || dev->current_state == PCI_D3hot)
+ msleep(pci_pm_d3_delay);
+ else if (state == PCI_D2 || dev->current_state == PCI_D2)
+ udelay(PCI_PM_D2_DELAY);
+
+ /* Check if the power state has actually changed */
+ pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL,
+ &new_pmcsr);
+ if (pmcsr == new_pmcsr) {
+ dev->current_state = state;
+ break;
+ }
+ } while (--attempts);
- dev->current_state = state;
+ if (pmcsr != new_pmcsr) {
+ dev->current_state = (new_pmcsr & PCI_PM_CTRL_STATE_MASK);
+ dev_warn(&dev->dev,
+ "failed to set power state to D%d, is D%d\n", state,
+ dev->current_state);
+ }
/* According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT
* INTERFACE SPECIFICATION, REV. 1.2", a device transitioning
@@ -540,9 +566,12 @@ void pci_update_current_state(struct pci
}
/**
- * pci_set_power_state - Set the power state of a PCI device
+ * __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.
+ * @attempts: How many times to try to change the power state of the device.
+ * @delay: Delay after programming the new power state, in miliseconds (0 means
+ * use default).
*
* Transition a device to a new power state, using the platform formware and/or
* the device's PCI PM registers.
@@ -554,7 +583,11 @@ void pci_update_current_state(struct pci
* 0 if device already is in the requested state.
* 0 if device's power state has been successfully changed.
*/
-int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
+int __pci_set_power_state(
+ struct pci_dev *dev,
+ pci_power_t state,
+ unsigned int attempts,
+ unsigned int delay)
{
int error;
@@ -590,7 +623,7 @@ int pci_set_power_state(struct pci_dev *
if (state == PCI_D3hot && (dev->dev_flags & PCI_DEV_FLAGS_NO_D3))
return 0;
- error = pci_raw_set_power_state(dev, state);
+ error = pci_raw_set_power_state(dev, state, attempts, delay);
if (state > PCI_D0 && platform_pci_power_manageable(dev)) {
/* Allow the platform to finalize the transition */
@@ -603,6 +636,7 @@ int pci_set_power_state(struct pci_dev *
return error;
}
+EXPORT_SYMBOL(__pci_set_power_state);
/**
* pci_choose_state - Choose the power state of a PCI device
@@ -2409,7 +2443,6 @@ EXPORT_SYMBOL(pci_assign_resource);
EXPORT_SYMBOL(pci_find_parent_resource);
EXPORT_SYMBOL(pci_select_bars);
-EXPORT_SYMBOL(pci_set_power_state);
EXPORT_SYMBOL(pci_save_state);
EXPORT_SYMBOL(pci_restore_state);
EXPORT_SYMBOL(pci_pme_capable);
Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -689,7 +689,12 @@ size_t pci_get_rom_size(struct pci_dev *
/* Power management related routines */
int pci_save_state(struct pci_dev *dev);
int pci_restore_state(struct pci_dev *dev);
-int pci_set_power_state(struct pci_dev *dev, pci_power_t state);
+int __pci_set_power_state(struct pci_dev *dev, pci_power_t state,
+ unsigned int attempts, unsigned int delay);
+static inline int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
+{
+ return __pci_set_power_state(dev, state, 1, 0);
+}
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);
void pci_pme_active(struct pci_dev *dev, bool enable);
--
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