kernel/linux.git/drivers/base/power/runtime.c, branch v5.4.239

PM: runtime: Do not call __rpm_callback() from rpm_idle()

2023-01-18T10:40:57+00:00

[ Upstream commit bc80c2e438dcbfcf748452ec0f7ad5b79ff3ad88 ] Calling __rpm_callback() from rpm_idle() after adding device links support to the former is a clear mistake. Not only it causes rpm_idle() to carry out unnecessary actions, but it is also against the assumption regarding the stability of PM-runtime status across __rpm_callback() invocations, because rpm_suspend() and rpm_resume() may run in parallel with __rpm_callback() when it is called by rpm_idle() and the device's PM-runtime status can be updated by any of them. Fixes: 21d5c57b3726 ("PM / runtime: Use device links") Link: https://lore.kernel.org/linux-pm/36aed941-a73e-d937-2721-4f0decd61ce0@quicinc.com Signed-off-by: Rafael J. Wysocki Reviewed-by: Adrian Hunter Signed-off-by: Sasha Levin

PM: runtime: Improve path in rpm_idle() when no callback

2023-01-18T10:40:57+00:00

[ Upstream commit 5a2bd1b1c64e1ac5627db3767ac465f18606315c ] When pm_runtime_no_callbacks() has been called for a struct device to set the dev->power.no_callbacks flag for it, it enables rpm_idle() to take a slightly quicker path by assuming that a ->runtime_idle() callback would have returned 0 to indicate success. A device that does not have the dev->power.no_callbacks flag set for it, may still be missing a corresponding ->runtime_idle() callback, in which case the slower path in rpm_idle() is taken. Let's improve the behaviour for this case, by aligning code to the quicker path. Signed-off-by: Ulf Hansson Acked-by: Alan Stern Signed-off-by: Rafael J. Wysocki Stable-dep-of: bc80c2e438dc ("PM: runtime: Do not call __rpm_callback() from rpm_idle()") Signed-off-by: Sasha Levin

PM: runtime: Fix unpaired parent child_count for force_resume

2021-05-19T08:08:20+00:00

commit c745253e2a691a40c66790defe85c104a887e14a upstream. As pm_runtime_need_not_resume() relies also on usage_count, it can return a different value in pm_runtime_force_suspend() compared to when called in pm_runtime_force_resume(). Different return values can happen if anything calls PM runtime functions in between, and causes the parent child_count to increase on every resume. So far I've seen the issue only for omapdrm that does complicated things with PM runtime calls during system suspend for legacy reasons: omap_atomic_commit_tail() for omapdrm.0 dispc_runtime_get() wakes up 58000000.dss as it's the dispc parent dispc_runtime_resume() rpm_resume() increases parent child_count dispc_runtime_put() won't idle, PM runtime suspend blocked pm_runtime_force_suspend() for 58000000.dss, !pm_runtime_need_not_resume() __update_runtime_status() system suspended pm_runtime_force_resume() for 58000000.dss, pm_runtime_need_not_resume() pm_runtime_enable() only called because of pm_runtime_need_not_resume() omap_atomic_commit_tail() for omapdrm.0 dispc_runtime_get() wakes up 58000000.dss as it's the dispc parent dispc_runtime_resume() rpm_resume() increases parent child_count dispc_runtime_put() won't idle, PM runtime suspend blocked ... rpm_suspend for 58000000.dss but parent child_count is now unbalanced Let's fix the issue by adding a flag for needs_force_resume and use it in pm_runtime_force_resume() instead of pm_runtime_need_not_resume(). Additionally omapdrm system suspend could be simplified later on to avoid lots of unnecessary PM runtime calls and the complexity it adds. The driver can just use internal functions that are shared between the PM runtime and system suspend related functions. Fixes: 4918e1f87c5f ("PM / runtime: Rework pm_runtime_force_suspend/resume()") Signed-off-by: Tony Lindgren Reviewed-by: Ulf Hansson Tested-by: Tomi Valkeinen Cc: 4.16+ # 4.16+ Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM: runtime: Fix ordering in pm_runtime_get_suppliers()

2021-04-07T12:47:42+00:00

commit c0c33442f7203704aef345647e14c2fb86071001 upstream. rpm_active indicates how many times the supplier usage_count has been incremented. Consequently it must be updated after pm_runtime_get_sync() of the supplier, not before. Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") Signed-off-by: Adrian Hunter Cc: 5.1+ # 5.1+ Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM: runtime: Fix race getting/putting suppliers at probe

2021-04-07T12:47:42+00:00

commit 9dfacc54a8661bc8be6e08cffee59596ec59f263 upstream. pm_runtime_put_suppliers() must not decrement rpm_active unless the consumer is suspended. That is because, otherwise, it could suspend suppliers for an active consumer. That can happen as follows: static int driver_probe_device(struct device_driver *drv, struct device *dev) { int ret = 0; if (!device_is_registered(dev)) return -ENODEV; dev->can_match = true; pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); pm_runtime_get_suppliers(dev); if (dev->parent) pm_runtime_get_sync(dev->parent); At this point, dev can runtime suspend so rpm_put_suppliers() can run, rpm_active becomes 1 (the lowest value). pm_runtime_barrier(dev); if (initcall_debug) ret = really_probe_debug(dev, drv); else ret = really_probe(dev, drv); Probe callback can have runtime resumed dev, and then runtime put so dev is awaiting autosuspend, but rpm_active is 2. pm_request_idle(dev); if (dev->parent) pm_runtime_put(dev->parent); pm_runtime_put_suppliers(dev); Now pm_runtime_put_suppliers() will put the supplier i.e. rpm_active 2 -> 1, but consumer can still be active. return ret; } Fix by checking the runtime status. For any status other than RPM_SUSPENDED, rpm_active can be considered to be "owned" by rpm_[get/put]_suppliers() and pm_runtime_put_suppliers() need do nothing. Reported-by: Asutosh Das Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance") Signed-off-by: Adrian Hunter Cc: 5.1+ # 5.1+ Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM: runtime: Defer suspending suppliers

2021-03-30T12:35:27+00:00

[ Upstream commit 5244f5e2d801259af877ee759e8c22364c607072 ] Because the PM-runtime status of the device is not updated in __rpm_callback(), attempts to suspend the suppliers of the given device triggered by the rpm_put_suppliers() call in there may cause a supplier to be suspended completely before the status of the consumer is updated to RPM_SUSPENDED, which is confusing. To avoid that (1) modify __rpm_callback() to only decrease the PM-runtime usage counter of each supplier and (2) make rpm_suspend() try to suspend the suppliers after changing the consumer's status to RPM_SUSPENDED, in analogy with the device's parent. Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/ Fixes: 21d5c57b3726 ("PM / runtime: Use device links") Reported-by: elaine.zhang Diagnosed-by: Ulf Hansson Reviewed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin

Revert "PM: runtime: Update device status before letting suppliers suspend"

2021-03-24T10:26:35+00:00

commit 0cab893f409c53634d0d818fa414641cbcdb0dab upstream. Revert commit 44cc89f76464 ("PM: runtime: Update device status before letting suppliers suspend") that introduced a race condition into __rpm_callback() which allowed a concurrent rpm_resume() to run and resume the device prematurely after its status had been changed to RPM_SUSPENDED by __rpm_callback(). Fixes: 44cc89f76464 ("PM: runtime: Update device status before letting suppliers suspend") Link: https://lore.kernel.org/linux-pm/24dfb6fc-5d54-6ee2-9195-26428b7ecf8a@intel.com/ Reported-by: Adrian Hunter Cc: 4.10+ # 4.10+ Signed-off-by: Rafael J. Wysocki Reviewed-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman

PM: runtime: Update device status before letting suppliers suspend

2021-03-09T10:09:37+00:00

commit 44cc89f764646b2f1f2ea5d1a08b230131707851 upstream. Because the PM-runtime status of the device is not updated in __rpm_callback(), attempts to suspend the suppliers of the given device triggered by rpm_put_suppliers() called by it may fail. Fix this by making __rpm_callback() update the device's status to RPM_SUSPENDED before calling rpm_put_suppliers() if the current status of the device is RPM_SUSPENDING and the callback just invoked by it has returned 0 (success). While at it, modify the code in __rpm_callback() to always check the device's PM-runtime status under its PM lock. Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/ Fixes: 21d5c57b3726 ("PM / runtime: Use device links") Reported-by: Elaine Zhang Diagnosed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki Tested-by: Elaine Zhang Reviewed-by: Ulf Hansson Cc: 4.10+ # 4.10+ Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

PM: runtime: Drop pm_runtime_clean_up_links()

2020-11-10T11:37:34+00:00

commit d6e36668598154820177bfd78c1621d8e6c580a2 upstream. After commit d12544fb2aa9 ("PM: runtime: Remove link state checks in rpm_get/put_supplier()") nothing prevents the consumer device's runtime PM from acquiring additional references to the supplier device after pm_runtime_clean_up_links() has run (or even while it is running), so calling this function from __device_release_driver() may be pointless (or even harmful). Moreover, it ignores stateless device links, so the runtime PM handling of managed and stateless device links is inconsistent because of it, so better get rid of it entirely. Fixes: d12544fb2aa9 ("PM: runtime: Remove link state checks in rpm_get/put_supplier()") Signed-off-by: Rafael J. Wysocki Cc: 5.1+ # 5.1+ Tested-by: Xiang Chen Reviewed-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

PM: runtime: Drop runtime PM references to supplier on link removal

2020-11-10T11:37:34+00:00

commit e0e398e204634db8fb71bd89cf2f6e3e5bd09b51 upstream. While removing a device link, drop the supplier device's runtime PM usage counter as many times as needed to drop all of the runtime PM references to it from the consumer in addition to dropping the consumer's link count. Fixes: baa8809f6097 ("PM / runtime: Optimize the use of device links") Signed-off-by: Rafael J. Wysocki Cc: 5.1+ # 5.1+ Tested-by: Xiang Chen Reviewed-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman