diff options
Diffstat (limited to 'include/linux/pm.h')
| -rw-r--r-- | include/linux/pm.h | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/include/linux/pm.h b/include/linux/pm.h index d915d0345fa1..72c0fe098a27 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -93,13 +93,23 @@ typedef struct pm_message { * been registered) to recover from the race condition. * This method is executed for all kinds of suspend transitions and is * followed by one of the suspend callbacks: @suspend(), @freeze(), or - * @poweroff(). The PM core executes subsystem-level @prepare() for all - * devices before starting to invoke suspend callbacks for any of them, so - * generally devices may be assumed to be functional or to respond to - * runtime resume requests while @prepare() is being executed. However, - * device drivers may NOT assume anything about the availability of user - * space at that time and it is NOT valid to request firmware from within - * @prepare() (it's too late to do that). It also is NOT valid to allocate + * @poweroff(). If the transition is a suspend to memory or standby (that + * is, not related to hibernation), the return value of @prepare() may be + * used to indicate to the PM core to leave the device in runtime suspend + * if applicable. Namely, if @prepare() returns a positive number, the PM + * core will understand that as a declaration that the device appears to be + * runtime-suspended and it may be left in that state during the entire + * transition and during the subsequent resume if all of its descendants + * are left in runtime suspend too. If that happens, @complete() will be + * executed directly after @prepare() and it must ensure the proper + * functioning of the device after the system resume. + * The PM core executes subsystem-level @prepare() for all devices before + * starting to invoke suspend callbacks for any of them, so generally + * devices may be assumed to be functional or to respond to runtime resume + * requests while @prepare() is being executed. However, device drivers + * may NOT assume anything about the availability of user space at that + * time and it is NOT valid to request firmware from within @prepare() + * (it's too late to do that). It also is NOT valid to allocate * substantial amounts of memory from @prepare() in the GFP_KERNEL mode. * [To work around these limitations, drivers may register suspend and * hibernation notifiers to be executed before the freezing of tasks.] @@ -112,7 +122,16 @@ typedef struct pm_message { * of the other devices that the PM core has unsuccessfully attempted to * suspend earlier). * The PM core executes subsystem-level @complete() after it has executed - * the appropriate resume callbacks for all devices. + * the appropriate resume callbacks for all devices. If the corresponding + * @prepare() at the beginning of the suspend transition returned a + * positive number and the device was left in runtime suspend (without + * executing any suspend and resume callbacks for it), @complete() will be + * the only callback executed for the device during resume. In that case, + * @complete() must be prepared to do whatever is necessary to ensure the + * proper functioning of the device after the system resume. To this end, + * @complete() can check the power.direct_complete flag of the device to + * learn whether (unset) or not (set) the previous suspend and resume + * callbacks have been executed for it. * * @suspend: Executed before putting the system into a sleep state in which the * contents of main memory are preserved. The exact action to perform @@ -546,6 +565,7 @@ struct dev_pm_info { bool is_late_suspended:1; bool ignore_children:1; bool early_init:1; /* Owned by the PM core */ + bool direct_complete:1; /* Owned by the PM core */ spinlock_t lock; #ifdef CONFIG_PM_SLEEP struct list_head entry; |