Commit 10aa5377 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Bjorn Helgaas
Browse files

PCI/PM: Split pci_raw_set_power_state() 

The transitions from low-power states to D0 and the other way around
are unnecessarily tangled in pci_raw_set_power_state() which makes it
rather hard to follow.

Moreover, the only caller of pci_raw_set_power_state() passing PCI_D0
as its state argument is pci_power_up(), so the code carrying out
transitions into D0 can be put directly into that function.

Accordingly, move the code handling transitions from low-power states
into D0 directly into pci_power_up() and rename the remaining part
of pci_raw_set_power_state() to pci_set_low_power_state(), because
it only handles transitions into low-power state now.

While at it, fix up some white space, update some comments and modify
messages printed by pci_power_up() and pci_set_low_power_state() to
be less confusing (which is the only expected functional impact of
this change).

Link: https://lore.kernel.org/r/13038676.uLZWGnKmhe@kreacher


Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 9c384ddd

drivers/pci/pci.c

+83 −60
Original line number Diff line number Diff line
@@ -1068,10 +1068,11 @@ static inline bool platform_pci_bridge_d3(struct pci_dev *dev) 
}



/**

 * pci_raw_set_power_state - Use PCI PM registers to set the power state of

 *			     given PCI device

 * pci_set_low_power_state - Put a PCI device into a low-power state.

 * @dev: PCI device to handle.

 * @state: PCI power state (D0, D1, D2, D3hot) to put the device into.

 * @state: PCI power state (D1, D2, D3hot) to put the device into.

 *

 * Use the device's PCI_PM_CTRL register to put it into a low-power state.

 *

 * RETURN VALUE:

 * -EINVAL if the requested state is invalid.
@@ -1080,10 +1081,9 @@ static inline bool platform_pci_bridge_d3(struct pci_dev *dev) 
 * 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_set_low_power_state(struct pci_dev *dev, pci_power_t state)

{

	u16 pmcsr;

	bool need_restore = false;



	/* Check if we're already there */

	if (dev->current_state == state)
@@ -1092,7 +1092,7 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) 
	if (!dev->pm_cap)

		return -EIO;



	if (state < PCI_D0 || state > PCI_D3hot)

	if (state < PCI_D1 || state > PCI_D3hot)

		return -EINVAL;



	/*
@@ -1101,8 +1101,7 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) 
	 * we can go from D1 to D3, but we can't go directly from D3 to D1;

	 * we'd have to go from D3 to D0, then to D1.

	 */

	if (state != PCI_D0 && dev->current_state <= PCI_D3cold

	    && dev->current_state > state) {

	if (dev->current_state <= PCI_D3cold && dev->current_state > state) {

		pci_err(dev, "invalid power transition (from %s to %s)\n",

			pci_power_name(dev->current_state),

			pci_power_name(state));
@@ -1116,71 +1115,31 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) 


	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);

	if (PCI_POSSIBLE_ERROR(pmcsr)) {

		pci_err(dev, "can't change power state from %s to %s (config space inaccessible)\n",

		pci_err(dev, "Unable to change power state from %s to %s, device inaccessible\n",

			pci_power_name(dev->current_state),

			pci_power_name(state));

		return -EIO;

	}



	/*

	 * If we're (effectively) in D3, force entire word to 0.

	 * This doesn't affect PME_Status, disables PME_En, and

	 * sets PowerState to 0.

	 */

	switch (dev->current_state) {

	case PCI_D0:

	case PCI_D1:

	case PCI_D2:

	pmcsr &= ~PCI_PM_CTRL_STATE_MASK;

	pmcsr |= state;

		break;

	case PCI_D3hot:

	case PCI_D3cold:

	case PCI_UNKNOWN: /* Boot-up */

		if ((pmcsr & PCI_PM_CTRL_STATE_MASK) == PCI_D3hot

		 && !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))

			need_restore = true;

		fallthrough;	/* force to D0 */

	default:

		pmcsr = 0;

		break;

	}



	/* Enter specified 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)

	/* Mandatory power management transition delays; see PCI PM 1.2. */

	if (state == PCI_D3hot)

		pci_dev_d3_sleep(dev);

	else if (state == PCI_D2 || dev->current_state == PCI_D2)

	else if (state == PCI_D2)

		udelay(PCI_PM_D2_DELAY);



	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);

	dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);

	dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;

	if (dev->current_state != state)

		pci_info_ratelimited(dev, "refused to change power state from %s to %s\n",

		pci_info_ratelimited(dev, "Refused to change power state from %s to %s\n",

				     pci_power_name(dev->current_state),

				     pci_power_name(state));



	/*

	 * According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT

	 * INTERFACE SPECIFICATION, REV. 1.2", a device transitioning

	 * from D3hot to D0 _may_ perform an internal reset, thereby

	 * going to "D0 Uninitialized" rather than "D0 Initialized".

	 * For example, at least some versions of the 3c905B and the

	 * 3c556B exhibit this behaviour.

	 *

	 * At least some laptop BIOSen (e.g. the Thinkpad T21) leave

	 * devices in a D3hot state at boot.  Consequently, we need to

	 * restore at least the BARs so that the device will be

	 * accessible to its driver.

	 */

	if (need_restore)

		pci_restore_bars(dev);



	if (dev->bus->self)

		pcie_aspm_pm_state_change(dev->bus->self);
@@ -1312,8 +1271,72 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout) 
 */

int pci_power_up(struct pci_dev *dev)

{

	bool need_restore = false;

	u16 pmcsr;



	pci_platform_power_transition(dev, PCI_D0);

	return pci_raw_set_power_state(dev, PCI_D0);



	if (dev->current_state == PCI_D0)

		return 0;



	if (!dev->pm_cap)

		return -EIO;



	pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);

	if (PCI_POSSIBLE_ERROR(pmcsr)) {

		pci_err(dev, "Unable to change power state from %s to D0, device inaccessible\n",

			pci_power_name(dev->current_state));

		return -EIO;

	}



	/*

	 * If we're (effectively) in D3, force entire word to 0. This doesn't

	 * affect PME_Status, disables PME_En, and sets PowerState to 0.

	 */

	if (dev->current_state >= PCI_D3hot) {

		if ((pmcsr & PCI_PM_CTRL_STATE_MASK) == PCI_D3hot &&

		    !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))

			need_restore = true;



		pmcsr = 0;

	} else {

		pmcsr &= ~PCI_PM_CTRL_STATE_MASK;

	}



	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, pmcsr);



	/* Mandatory transition delays; see PCI PM 1.2. */

	if (dev->current_state == PCI_D3hot)

		pci_dev_d3_sleep(dev);

	else if (dev->current_state == PCI_D2)

		udelay(PCI_PM_D2_DELAY);



	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));



	/*

	 * According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT

	 * INTERFACE SPECIFICATION, REV. 1.2", a device transitioning

	 * from D3hot to D0 _may_ perform an internal reset, thereby

	 * going to "D0 Uninitialized" rather than "D0 Initialized".

	 * For example, at least some versions of the 3c905B and the

	 * 3c556B exhibit this behaviour.

	 *

	 * At least some laptop BIOSen (e.g. the Thinkpad T21) leave

	 * devices in a D3hot state at boot.  Consequently, we need to

	 * restore at least the BARs so that the device will be

	 * accessible to its driver.

	 */

	if (need_restore)

		pci_restore_bars(dev);



	if (dev->bus->self)

		pcie_aspm_pm_state_change(dev->bus->self);



	return 0;

}



/**
@@ -1394,7 +1417,7 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state) 
	 * To put device in D3cold, we put device into D3hot in native

	 * way, then put device into D3cold with platform ops

	 */

	error = pci_raw_set_power_state(dev, state > PCI_D3hot ?

	error = pci_set_low_power_state(dev, state > PCI_D3hot ?

					PCI_D3hot : state);



	if (pci_platform_power_transition(dev, state))