| Message ID | 3252449.XN2pzxrAPQ@vostro.rjw.lan (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
On Wed, 2015-06-10 at 02:08 +0200, Rafael J. Wysocki wrote: > On Tuesday, June 09, 2015 01:42:00 AM Rafael J. Wysocki wrote: > > On Monday, June 01, 2015 05:47:57 PM Andy Shevchenko wrote: > > > From: Heikki Krogerus <heikki.krogerus@linux.intel.com> > > > > > > If the parent is still suspended when driver probe is > > > attempted, the result may be failure. > > > > > > For example, if the parent is a PCI MFD device that has been > > > suspended when we try to probe our device, any register > > > reads will return 0xffffffff. > > > > > > To fix the problem, making sure the parent is always awake > > > before attempting driver probe. > > > > > > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > > --- > > > drivers/base/dd.c | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > > > index e843fdb..cfbeff3 100644 > > > --- a/drivers/base/dd.c > > > +++ b/drivers/base/dd.c > > > @@ -399,6 +399,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe); > > > * > > > * This function must be called with @dev lock held. When called for a > > > * USB interface, @dev->parent lock must be held as well. > > > + * > > > + * If device has a parent it will be powered on during device's probe(). > > > */ > > > int driver_probe_device(struct device_driver *drv, struct device *dev) > > > { > > > @@ -410,10 +412,16 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > > > pr_debug("bus: '%s': %s: matched device %s with driver %s\n", > > > drv->bus->name, __func__, dev_name(dev), drv->name); > > > > > > + if (dev->parent) > > > + pm_runtime_get_sync(dev->parent); > > > + > > > > For some bus types that will resume and suspend the parent for many times in > > a row in device_attach() until an appropriate driver is found. Would it be > > more efficient to call it once before the bus_for_each_drv() loop in there? > > Actually, something like the below should work too (the bumping up of the > parent's usage counter before the loop will keep it in the runtime-active > state throughout the loop). > Thanks for the patch! We are going to test this soon. By the way, can you give your Ack for patches 1 and 2 if there is no objection? > --- > drivers/base/dd.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > Index: linux-pm/drivers/base/dd.c > =================================================================== > --- linux-pm.orig/drivers/base/dd.c > +++ linux-pm/drivers/base/dd.c > @@ -399,6 +399,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe) > * > * This function must be called with @dev lock held. When called for a > * USB interface, @dev->parent lock must be held as well. > + * > + * If the device has a parent, runtime-resume the parent before driver probing. > */ > int driver_probe_device(struct device_driver *drv, struct device *dev) > { > @@ -410,10 +412,16 @@ int driver_probe_device(struct device_dr > pr_debug("bus: '%s': %s: matched device %s with driver %s\n", > drv->bus->name, __func__, dev_name(dev), drv->name); > > + if (dev->parent) > + pm_runtime_get_sync(dev->parent); > + > pm_runtime_barrier(dev); > ret = really_probe(dev, drv); > pm_request_idle(dev); > > + if (dev->parent) > + pm_runtime_put(dev->parent); > + > return ret; > } > > @@ -459,8 +467,14 @@ int device_attach(struct device *dev) > ret = 0; > } > } else { > + if (dev->parent) > + pm_runtime_get_sync(dev->parent); > + > ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); > pm_request_idle(dev); > + > + if (dev->parent) > + pm_runtime_put(dev->parent); > } > out_unlock: > device_unlock(dev); >
On Wed, 2015-06-10 at 02:08 +0200, Rafael J. Wysocki wrote: > On Tuesday, June 09, 2015 01:42:00 AM Rafael J. Wysocki wrote: > > On Monday, June 01, 2015 05:47:57 PM Andy Shevchenko wrote: > > > From: Heikki Krogerus <heikki.krogerus@linux.intel.com> > > > > > > If the parent is still suspended when driver probe is > > > attempted, the result may be failure. > > > > > > For example, if the parent is a PCI MFD device that has been > > > suspended when we try to probe our device, any register > > > reads will return 0xffffffff. > > > > > > To fix the problem, making sure the parent is always awake > > > before attempting driver probe. [] > Actually, something like the below should work too (the bumping up of the > parent's usage counter before the loop will keep it in the runtime-active > state throughout the loop). It works. Thanks for the patch. We incorporate it instead of the previous Heikki's patch into v4.
On Wednesday, June 10, 2015 12:43:15 PM Andy Shevchenko wrote: > On Wed, 2015-06-10 at 02:08 +0200, Rafael J. Wysocki wrote: > > On Tuesday, June 09, 2015 01:42:00 AM Rafael J. Wysocki wrote: > > > On Monday, June 01, 2015 05:47:57 PM Andy Shevchenko wrote: > > > > From: Heikki Krogerus <heikki.krogerus@linux.intel.com> > > > > > > > > If the parent is still suspended when driver probe is > > > > attempted, the result may be failure. > > > > > > > > For example, if the parent is a PCI MFD device that has been > > > > suspended when we try to probe our device, any register > > > > reads will return 0xffffffff. > > > > > > > > To fix the problem, making sure the parent is always awake > > > > before attempting driver probe. > > > > > > > > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > > > --- > > > > drivers/base/dd.c | 8 ++++++++ > > > > 1 file changed, 8 insertions(+) > > > > > > > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > > > > index e843fdb..cfbeff3 100644 > > > > --- a/drivers/base/dd.c > > > > +++ b/drivers/base/dd.c > > > > @@ -399,6 +399,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe); > > > > * > > > > * This function must be called with @dev lock held. When called for a > > > > * USB interface, @dev->parent lock must be held as well. > > > > + * > > > > + * If device has a parent it will be powered on during device's probe(). > > > > */ > > > > int driver_probe_device(struct device_driver *drv, struct device *dev) > > > > { > > > > @@ -410,10 +412,16 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > > > > pr_debug("bus: '%s': %s: matched device %s with driver %s\n", > > > > drv->bus->name, __func__, dev_name(dev), drv->name); > > > > > > > > + if (dev->parent) > > > > + pm_runtime_get_sync(dev->parent); > > > > + > > > > > > For some bus types that will resume and suspend the parent for many times in > > > a row in device_attach() until an appropriate driver is found. Would it be > > > more efficient to call it once before the bus_for_each_drv() loop in there? > > > > Actually, something like the below should work too (the bumping up of the > > parent's usage counter before the loop will keep it in the runtime-active > > state throughout the loop). > > > > Thanks for the patch! We are going to test this soon. > > By the way, can you give your Ack for patches 1 and 2 if there is no > objection? OK
Index: linux-pm/drivers/base/dd.c =================================================================== --- linux-pm.orig/drivers/base/dd.c +++ linux-pm/drivers/base/dd.c @@ -399,6 +399,8 @@ EXPORT_SYMBOL_GPL(wait_for_device_probe) * * This function must be called with @dev lock held. When called for a * USB interface, @dev->parent lock must be held as well. + * + * If the device has a parent, runtime-resume the parent before driver probing. */ int driver_probe_device(struct device_driver *drv, struct device *dev) { @@ -410,10 +412,16 @@ int driver_probe_device(struct device_dr pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); + if (dev->parent) + pm_runtime_get_sync(dev->parent); + pm_runtime_barrier(dev); ret = really_probe(dev, drv); pm_request_idle(dev); + if (dev->parent) + pm_runtime_put(dev->parent); + return ret; } @@ -459,8 +467,14 @@ int device_attach(struct device *dev) ret = 0; } } else { + if (dev->parent) + pm_runtime_get_sync(dev->parent); + ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); pm_request_idle(dev); + + if (dev->parent) + pm_runtime_put(dev->parent); } out_unlock: device_unlock(dev);