Re: [PATCH v2] PM / Runtime: let rpm_resume() succeed if RPM_ACTIVE, even when disabled
On Saturday, September 22, 2012, Kevin Hilman wrote:
From: Kevin Hilman khil...@ti.com
There are several drivers where the return value of
pm_runtime_get_sync() is used to decide whether or not it is safe to
access hardware and that don't provide .suspend() callbacks for system
suspend (but may use late/noirq callbacks.) If such a driver happens
to call pm_runtime_get_sync() during system suspend, after the core
has disabled runtime PM, it will get the error code and will decide
that the hardware should not be accessed, although this may be a wrong
conclusion, depending on the state of the device when runtime PM was
disabled.
Drivers might work around this problem by using a test like:
ret = pm_runtime_get_sync(dev);
if (!ret || (ret == -EACCES driver_private_data(dev)-suspended)) {
/* access hardware */
}
where driver_private_data(dev)-suspended is a flag set by the
driver's .suspend() method (that would have to be added for this
purpose). However, that potentially would need to be done by multiple
drivers which means quite a lot of duplicated code and bloat.
To avoid that we can use the observation that the core sets
dev-power.is_suspended before disabling runtime PM and use that
instead of the driver's private flag. Still, potentially many drivers
would need to repeat that same check in quite a few places, so it's
better to let the core do it.
Then we can be a bit smarter and check whether or not runtime PM was
disabled by the core only (disable_depth == 1) or by someone else in
addition to the core (disable_depth 1). In the former case
rpm_resume() can return 1 if the runtime PM status is RPM_ACTIVE,
because it means the device was active when the core disabled runtime
PM. In the latter case it should still return -EACCES, because it
isn't clear why runtime PM has been disabled.
Tested on AM3730/Beagle-xM where a wakeup IRQ firing during the late
suspend phase triggers runtime PM activity in the I2C driver since the
wakeup IRQ is on an I2C-connected PMIC.
Cc: Rafael J. Wysocki r...@sisk.pl
Cc: Alan Stern st...@rowland.harvard.edu
Signed-off-by: Kevin Hilman khil...@ti.com
---
v2:
- major changelog rewrite, based largely on input from Rafael
- add check for disable_depth == 1 and move to separate if statement,
both suggested by Alan Stern
OK, this looks good to me, thanks!
Alan, what do you think?
Rafael
drivers/base/power/runtime.c |3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 7d9c1cb..d43856b 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -509,6 +509,9 @@ static int rpm_resume(struct device *dev, int rpmflags)
repeat:
if (dev-power.runtime_error)
retval = -EINVAL;
+ else if (dev-power.disable_depth == 1 dev-power.is_suspended
+ dev-power.runtime_status == RPM_ACTIVE)
+ retval = 1;
else if (dev-power.disable_depth 0)
retval = -EACCES;
if (retval)
--
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Re: [PATCH v2] PM / Runtime: let rpm_resume() succeed if RPM_ACTIVE, even when disabled
On Saturday, September 22, 2012, Alan Stern wrote: On Sat, 22 Sep 2012, Rafael J. Wysocki wrote: On Saturday, September 22, 2012, Kevin Hilman wrote: OK, this looks good to me, thanks! Alan, what do you think? Rafael --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -509,6 +509,9 @@ static int rpm_resume(struct device *dev, int rpmflags) repeat: if (dev-power.runtime_error) retval = -EINVAL; + else if (dev-power.disable_depth == 1 dev-power.is_suspended + dev-power.runtime_status == RPM_ACTIVE) + retval = 1; else if (dev-power.disable_depth 0) retval = -EACCES; if (retval) Well, I'd prefer the indentation on the continuation line to be different from the indentation of the following line, and I'd prefer to have a comment explaining the reason for the exception. But these are only matters of taste; the implementation itself looks good. Thanks! I've applied the patch as v3.7 material (and fixed up the white space). Rafael -- To unsubscribe from this list: send the line unsubscribe linux-omap in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH v2] PM / Runtime: let rpm_resume() succeed if RPM_ACTIVE, even when disabled
From: Kevin Hilman khil...@ti.com
There are several drivers where the return value of
pm_runtime_get_sync() is used to decide whether or not it is safe to
access hardware and that don't provide .suspend() callbacks for system
suspend (but may use late/noirq callbacks.) If such a driver happens
to call pm_runtime_get_sync() during system suspend, after the core
has disabled runtime PM, it will get the error code and will decide
that the hardware should not be accessed, although this may be a wrong
conclusion, depending on the state of the device when runtime PM was
disabled.
Drivers might work around this problem by using a test like:
ret = pm_runtime_get_sync(dev);
if (!ret || (ret == -EACCES driver_private_data(dev)-suspended)) {
/* access hardware */
}
where driver_private_data(dev)-suspended is a flag set by the
driver's .suspend() method (that would have to be added for this
purpose). However, that potentially would need to be done by multiple
drivers which means quite a lot of duplicated code and bloat.
To avoid that we can use the observation that the core sets
dev-power.is_suspended before disabling runtime PM and use that
instead of the driver's private flag. Still, potentially many drivers
would need to repeat that same check in quite a few places, so it's
better to let the core do it.
Then we can be a bit smarter and check whether or not runtime PM was
disabled by the core only (disable_depth == 1) or by someone else in
addition to the core (disable_depth 1). In the former case
rpm_resume() can return 1 if the runtime PM status is RPM_ACTIVE,
because it means the device was active when the core disabled runtime
PM. In the latter case it should still return -EACCES, because it
isn't clear why runtime PM has been disabled.
Tested on AM3730/Beagle-xM where a wakeup IRQ firing during the late
suspend phase triggers runtime PM activity in the I2C driver since the
wakeup IRQ is on an I2C-connected PMIC.
Cc: Rafael J. Wysocki r...@sisk.pl
Cc: Alan Stern st...@rowland.harvard.edu
Signed-off-by: Kevin Hilman khil...@ti.com
---
v2:
- major changelog rewrite, based largely on input from Rafael
- add check for disable_depth == 1 and move to separate if statement,
both suggested by Alan Stern
drivers/base/power/runtime.c |3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 7d9c1cb..d43856b 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -509,6 +509,9 @@ static int rpm_resume(struct device *dev, int rpmflags)
repeat:
if (dev-power.runtime_error)
retval = -EINVAL;
+ else if (dev-power.disable_depth == 1 dev-power.is_suspended
+ dev-power.runtime_status == RPM_ACTIVE)
+ retval = 1;
else if (dev-power.disable_depth 0)
retval = -EACCES;
if (retval)
--
1.7.9.2
--
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