diff options
author | Ohad Ben-Cohen <ohad@wizery.com> | 2010-10-02 15:54:13 +0400 |
---|---|---|
committer | Chris Ball <cjb@laptop.org> | 2010-10-23 17:11:19 +0400 |
commit | ed2a9785942b0986ac858f3f48d7fc5f7c7183de (patch) | |
tree | 31853b8ba7ab7ee06fbd5bbf08c9e94fca091631 /drivers/mmc/core | |
parent | 87973ba27b751353e2915cb3aa5c0e0dc6a79a4f (diff) | |
download | linux-ed2a9785942b0986ac858f3f48d7fc5f7c7183de.tar.xz |
mmc: sdio: support suspend/resume while runtime suspended
Bring SDIO devices back to full power before their suspend
handler is invoked.
Doing so ensures that SDIO suspend/resume semantics are
maintained (drivers still get to decide whether their
card should be removed or kept during system suspend,
and at what power state), and that SDIO suspend/resume
execution paths are unchanged.
This is achieved by resuming a runtime-suspended SDIO device
in its ->prepare() PM callback (similary to the PCI subsystem).
Since the PM core always increments the run-time usage
counter before calling the ->prepare() callback and decrements
it after calling the ->complete() callback, it is guaranteed
that when the system will come out of suspend, our device's
power state will reflect its runtime PM usage counter.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc/core')
-rw-r--r-- | drivers/mmc/core/sdio_bus.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/mmc/core/sdio_bus.c b/drivers/mmc/core/sdio_bus.c index 36374834fcff..2716c7ab6bbf 100644 --- a/drivers/mmc/core/sdio_bus.c +++ b/drivers/mmc/core/sdio_bus.c @@ -189,12 +189,41 @@ out: #ifdef CONFIG_PM_RUNTIME +static int sdio_bus_pm_prepare(struct device *dev) +{ + /* + * Resume an SDIO device which was suspended at run time at this + * point, in order to allow standard SDIO suspend/resume paths + * to keep working as usual. + * + * Ultimately, the SDIO driver itself will decide (in its + * suspend handler, or lack thereof) whether the card should be + * removed or kept, and if kept, at what power state. + * + * At this point, PM core have increased our use count, so it's + * safe to directly resume the device. After system is resumed + * again, PM core will drop back its runtime PM use count, and if + * needed device will be suspended again. + * + * The end result is guaranteed to be a power state that is + * coherent with the device's runtime PM use count. + * + * The return value of pm_runtime_resume is deliberately unchecked + * since there is little point in failing system suspend if a + * device can't be resumed. + */ + pm_runtime_resume(dev); + + return 0; +} + static const struct dev_pm_ops sdio_bus_pm_ops = { SET_RUNTIME_PM_OPS( pm_generic_runtime_suspend, pm_generic_runtime_resume, pm_generic_runtime_idle ) + .prepare = sdio_bus_pm_prepare, }; #define SDIO_PM_OPS_PTR (&sdio_bus_pm_ops) |