Re: [PATCH v2] PCI / PM: Avoid using device_may_wakeup() for runtime PM

Bjorn Helgaas
2017-06-30T16:16:55Z

On Fri, Jun 23, 2017 at 02:58:11PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> pci_target_state() calls device_may_wakeup() which checks whether
> or not the device may wake up the system from sleep states, but
> pci_target_state() is used for runtime PM too.
>
> Since runtime PM is expected to always enable remote wakeup if
> possible, modify pci_target_state() to take additional argument
> indicating whether or not it should look for a state from which
> the device can signal wakeup and pass either the return value
> of device_can_wakeup(), or "false" (if the device itself is not
> wakeup-capable) to it from the code related to runtime PM.
>
> While at it, fix the comment in pci_dev_run_wake() which is not
> about sleep states.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Applied with Mika's reviewed-by to pci/pm for v4.13, thanks!

> ---
>
> -> v2:
>
> Passing "true" as the second argument to pci_target_state() for runtime PM
> might trigger suboptimal state choices to be made, so pass the return value
> of device_can_wakeup() to it instead and pass "false" to it in pci_dev_run_wake(),
> because that assumes device_can_wakeup() to return "false" already.
>
> ---
> drivers/pci/pci.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> Index: linux-pm/drivers/pci/pci.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci.c
> +++ linux-pm/drivers/pci/pci.c
> @@ -1982,12 +1982,13 @@ EXPORT_SYMBOL(pci_wake_from_d3);
> /**
> * pci_target_state - find an appropriate low power state for a given PCI dev
> * @dev: PCI device
> + * @wakeup: Whether or not wakeup functionality will be enabled for the device.
> *
> * Use underlying platform code to find a supported low power state for @dev.
> * If the platform can't manage @dev, return the deepest state from which it
> * can generate wake events, based on any available PME info.
> */
> -static pci_power_t pci_target_state(struct pci_dev *dev)
> +static pci_power_t pci_target_state(struct pci_dev *dev, bool wakeup)
> {
> pci_power_t target_state = PCI_D3hot;
>
> @@ -2024,7 +2025,7 @@ static pci_power_t pci_target_state(stru
> if (dev->current_state == PCI_D3cold)
> target_state = PCI_D3cold;
>
> - if (device_may_wakeup(&dev->dev)) {
> + if (wakeup) {
> /*
> * Find the deepest state from which the device can generate
> * wake-up events, make it the target state and enable device
> @@ -2050,13 +2051,14 @@ static pci_power_t pci_target_state(stru
> */
> int pci_prepare_to_sleep(struct pci_dev *dev)
> {
> - pci_power_t target_state = pci_target_state(dev);
> + bool wakeup = device_may_wakeup(&dev->dev);
> + pci_power_t target_state = pci_target_state(dev, wakeup);
> int error;
>
> if (target_state == PCI_POWER_ERROR)
> return -EIO;
>
> - pci_enable_wake(dev, target_state, device_may_wakeup(&dev->dev));
> + pci_enable_wake(dev, target_state, wakeup);
>
> error = pci_set_power_state(dev, target_state);
>
> @@ -2089,9 +2091,10 @@ EXPORT_SYMBOL(pci_back_from_sleep);
> */
> int pci_finish_runtime_suspend(struct pci_dev *dev)
> {
> - pci_power_t target_state = pci_target_state(dev);
> + pci_power_t target_state;
> int error;
>
> + target_state = pci_target_state(dev, device_can_wakeup(&dev->dev));
> if (target_state == PCI_POWER_ERROR)
> return -EIO;
>
> @@ -2127,8 +2130,8 @@ bool pci_dev_run_wake(struct pci_dev *de
> if (!dev->pme_support)
> return false;
>
> - /* PME-capable in principle, but not from the intended sleep state */
> - if (!pci_pme_capable(dev, pci_target_state(dev)))
> + /* PME-capable in principle, but not from the target power state */
> + if (!pci_pme_capable(dev, pci_target_state(dev, false)))
> return false;
>
> while (bus->parent) {
> @@ -2163,9 +2166,10 @@ EXPORT_SYMBOL_GPL(pci_dev_run_wake);
> bool pci_dev_keep_suspended(struct pci_dev *pci_dev)
> {
> struct device *dev = &pci_dev->dev;
> + bool wakeup = device_may_wakeup(dev);
>
> if (!pm_runtime_suspended(dev)
> - || pci_target_state(pci_dev) != pci_dev->current_state
> + || pci_target_state(pci_dev, wakeup) != pci_dev->current_state
> || platform_pci_need_resume(pci_dev)
> || (pci_dev->dev_flags & PCI_DEV_FLAGS_NEEDS_RESUME))
> return false;
> @@ -2183,7 +2187,7 @@ bool pci_dev_keep_suspended(struct pci_d
> spin_lock_irq(&dev->power.lock);
>
> if (pm_runtime_suspended(dev) && pci_dev->current_state < PCI_D3cold &&
> - !device_may_wakeup(dev))
> + !wakeup)
> __pci_pme_active(pci_dev, false);
>
> spin_unlock_irq(&dev->power.lock);
>