diff options
| -rw-r--r-- | Documentation/power/pci.txt | 51 | ||||
| -rw-r--r-- | drivers/acpi/pci_irq.c | 1 | ||||
| -rw-r--r-- | drivers/acpi/pci_link.c | 16 | ||||
| -rw-r--r-- | drivers/pci/pci-driver.c | 7 | ||||
| -rw-r--r-- | include/linux/acpi.h | 1 |
5 files changed, 58 insertions, 18 deletions
diff --git a/Documentation/power/pci.txt b/Documentation/power/pci.txt index 62328d76b55b..b0e911e0e8f5 100644 --- a/Documentation/power/pci.txt +++ b/Documentation/power/pci.txt @@ -979,20 +979,45 @@ every time right after the runtime_resume() callback has returned (alternatively, the runtime_suspend() callback will have to check if the device should really be suspended and return -EAGAIN if that is not the case). -The runtime PM of PCI devices is disabled by default. It is also blocked by -pci_pm_init() that runs the pm_runtime_forbid() helper function. If a PCI -driver implements the runtime PM callbacks and intends to use the runtime PM -framework provided by the PM core and the PCI subsystem, it should enable this -feature by executing the pm_runtime_enable() helper function. However, the -driver should not call the pm_runtime_allow() helper function unblocking -the runtime PM of the device. Instead, it should allow user space or some -platform-specific code to do that (user space can do it via sysfs), although -once it has called pm_runtime_enable(), it must be prepared to handle the +The runtime PM of PCI devices is enabled by default by the PCI core. PCI +device drivers do not need to enable it and should not attempt to do so. +However, it is blocked by pci_pm_init() that runs the pm_runtime_forbid() +helper function. In addition to that, the runtime PM usage counter of +each PCI device is incremented by local_pci_probe() before executing the +probe callback provided by the device's driver. + +If a PCI driver implements the runtime PM callbacks and intends to use the +runtime PM framework provided by the PM core and the PCI subsystem, it needs +to decrement the device's runtime PM usage counter in its probe callback +function. If it doesn't do that, the counter will always be different from +zero for the device and it will never be runtime-suspended. The simplest +way to do that is by calling pm_runtime_put_noidle(), but if the driver +wants to schedule an autosuspend right away, for example, it may call +pm_runtime_put_autosuspend() instead for this purpose. Generally, it +just needs to call a function that decrements the devices usage counter +from its probe routine to make runtime PM work for the device. + +It is important to remember that the driver's runtime_suspend() callback +may be executed right after the usage counter has been decremented, because +user space may already have cuased the pm_runtime_allow() helper function +unblocking the runtime PM of the device to run via sysfs, so the driver must +be prepared to cope with that. + +The driver itself should not call pm_runtime_allow(), though. Instead, it +should let user space or some platform-specific code do that (user space can +do it via sysfs as stated above), but it must be prepared to handle the runtime PM of the device correctly as soon as pm_runtime_allow() is called -(which may happen at any time). [It also is possible that user space causes -pm_runtime_allow() to be called via sysfs before the driver is loaded, so in -fact the driver has to be prepared to handle the runtime PM of the device as -soon as it calls pm_runtime_enable().] +(which may happen at any time, even before the driver is loaded). + +When the driver's remove callback runs, it has to balance the decrementation +of the device's runtime PM usage counter at the probe time. For this reason, +if it has decremented the counter in its probe callback, it must run +pm_runtime_get_noresume() in its remove callback. [Since the core carries +out a runtime resume of the device and bumps up the device's usage counter +before running the driver's remove callback, the runtime PM of the device +is effectively disabled for the duration of the remove execution and all +runtime PM helper functions incrementing the device's usage counter are +then effectively equivalent to pm_runtime_get_noresume().] The runtime PM framework works by processing requests to suspend or resume devices, or to check if they are idle (in which cases it is reasonable to diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c index 6da0f9beab19..c9336751e5e3 100644 --- a/drivers/acpi/pci_irq.c +++ b/drivers/acpi/pci_irq.c @@ -372,6 +372,7 @@ static int acpi_isa_register_gsi(struct pci_dev *dev) /* Interrupt Line values above 0xF are forbidden */ if (dev->irq > 0 && (dev->irq <= 0xF) && + acpi_isa_irq_available(dev->irq) && (acpi_isa_irq_to_gsi(dev->irq, &dev_gsi) == 0)) { dev_warn(&dev->dev, "PCI INT %c: no GSI - using ISA IRQ %d\n", pin_name(dev->pin), dev->irq); diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c index 3b4ea98e3ea0..7c8408b946ca 100644 --- a/drivers/acpi/pci_link.c +++ b/drivers/acpi/pci_link.c @@ -498,8 +498,7 @@ int __init acpi_irq_penalty_init(void) PIRQ_PENALTY_PCI_POSSIBLE; } } - /* Add a penalty for the SCI */ - acpi_irq_penalty[acpi_gbl_FADT.sci_interrupt] += PIRQ_PENALTY_PCI_USING; + return 0; } @@ -553,6 +552,13 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) irq = link->irq.possible[i]; } } + if (acpi_irq_penalty[irq] >= PIRQ_PENALTY_ISA_ALWAYS) { + printk(KERN_ERR PREFIX "No IRQ available for %s [%s]. " + "Try pci=noacpi or acpi=off\n", + acpi_device_name(link->device), + acpi_device_bid(link->device)); + return -ENODEV; + } /* Attempt to enable the link device at this IRQ. */ if (acpi_pci_link_set(link, irq)) { @@ -821,6 +827,12 @@ void acpi_penalize_isa_irq(int irq, int active) } } +bool acpi_isa_irq_available(int irq) +{ + return irq >= 0 && (irq >= ARRAY_SIZE(acpi_irq_penalty) || + acpi_irq_penalty[irq] < PIRQ_PENALTY_ISA_ALWAYS); +} + /* * Penalize IRQ used by ACPI SCI. If ACPI SCI pin attributes conflict with * PCI IRQ attributes, mark ACPI SCI as ISA_ALWAYS so it won't be use for diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index dd652f2ae03d..108a3118ace7 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -299,9 +299,10 @@ static long local_pci_probe(void *_ddi) * Unbound PCI devices are always put in D0, regardless of * runtime PM status. During probe, the device is set to * active and the usage count is incremented. If the driver - * supports runtime PM, it should call pm_runtime_put_noidle() - * in its probe routine and pm_runtime_get_noresume() in its - * remove routine. + * supports runtime PM, it should call pm_runtime_put_noidle(), + * or any other runtime PM helper function decrementing the usage + * count, in its probe routine and pm_runtime_get_noresume() in + * its remove routine. */ pm_runtime_get_sync(dev); pci_dev->driver = pci_drv; diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 7235c4851460..43856d19cf4d 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -217,6 +217,7 @@ struct pci_dev; int acpi_pci_irq_enable (struct pci_dev *dev); void acpi_penalize_isa_irq(int irq, int active); +bool acpi_isa_irq_available(int irq); void acpi_penalize_sci_irq(int irq, int trigger, int polarity); void acpi_pci_irq_disable (struct pci_dev *dev); |