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SubjectRe: Recent "Run the driver callback directly" patch breaks libertas suspend
Date
On Sunday, March 25, 2012, Rafael J. Wysocki wrote:
> Hi,
>
> On Sunday, March 25, 2012, NeilBrown wrote:
> >
> > Hi Rafael,
> >
> > Your recent patch:
> > commit 35cd133c
> > PM: Run the driver callback directly if the subsystem one is not there
> >
> > breaks suspend for my libertas wifi and probably other SDIO devices.
>
> Well, the patch is not recent. The _commit_ is more than three months old
> and the patch has been around since the last November (at least).
>
> > SDIO (and possible MMC in general) has a protocol where the suspend
> > method can return -ENOSYS and this means "There is no point in suspending,
> > just turn me off".
> >
> > The device itself "mmc1:0001" (I think) doesn't have any bus etc 'suspend'
> > function so the new code call the device's suspend function which returns
> > ENOSYS and the suspend fails.
> >
> > The previous code ignores the device as there is no bus suspend, and when it
> > gets to suspend the ancestor - which for me is omap_hsmmc.1, it calls the
> > device suspend function catches the ENOSYS, and turns it off.
>
> Well, I can only call that a blatant abuse of the PM infrastructure.
>
> > I suspect just reverting it isn't the right long term solution, however I
> > can confirm that it works for me for now.
>
> It's not a solution at all, because there's code that depends on it already in
> the tree and the fact that it works for you doesn't mean it won't break other
> systems. So no, it's not an option.
>
> > I'm happy to try any alternate fixes you would like to suggest (but I cannot
> > promise how quickly I will get the testing done).
> >
> > (I'm testing with 3.3)
>
> The only fix I can think of is to rework SDIO to stop abusing the PM callbacks.
> I'll have a look at that next week, although I can't promise anything any time
> soon, because I'm heading to San Francisco on Saturday.

Well, this is kind of a long shot, but I wonder if the patch below makes
any difference?

Rafael

---
drivers/mmc/core/sdio_bus.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
Index: linux/drivers/mmc/core/sdio_bus.c
===================================================================
--- linux.orig/drivers/mmc/core/sdio_bus.c
+++ linux/drivers/mmc/core/sdio_bus.c
@@ -192,9 +192,15 @@ static int sdio_bus_remove(struct device
return ret;
}

-#ifdef CONFIG_PM_RUNTIME
+#ifdef CONFIG_PM
+
+static int pm_no_operation(struct device *dev)
+{
+ return 0;
+}

static const struct dev_pm_ops sdio_bus_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(pm_no_operation, pm_no_operation)
SET_RUNTIME_PM_OPS(
pm_generic_runtime_suspend,
pm_generic_runtime_resume,
@@ -204,11 +210,11 @@ static const struct dev_pm_ops sdio_bus_

#define SDIO_PM_OPS_PTR (&sdio_bus_pm_ops)

-#else /* !CONFIG_PM_RUNTIME */
+#else /* !CONFIG_PM */

#define SDIO_PM_OPS_PTR NULL

-#endif /* !CONFIG_PM_RUNTIME */
+#endif /* !CONFIG_PM */

static struct bus_type sdio_bus_type = {
.name = "sdio",

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