On Thu, Jun 17, 2010 at 7:02 PM, Rafael J. Wysocki rjw@sisk.pl wrote:
From: Rafael J. Wysocki rjw@sisk.pl
There is a regression from 2.6.34 related to the recent radeon power management changes, caused by attempting to cancel a delayed work item that's never been scheduled. However, the code as is has some other issues potentially leading to visible problems.
First, the mutex around cancel_delayed_work() in radeon_pm_suspend() doesn't really serve any purpose, because cancel_delayed_work() only tries to delete the work's timer. Moreover, it doesn't prevent the work handler from running, so the handler can do some wrong things if it wins the race and in that case it will rearm itself to do some more wrong things going forward. So, I think it's better to wait for the handler to return in case it's already been queued up for execution. Also, it should be prevented from rearming itself in that case.
Second, in radeon_set_pm_method() the cancel_delayed_work() is not sufficient to prevent the work handler from running and queing up itself for the next run (the failure scenario is that cancel_delayed_work() returns 0, so the handler is run, it waits on the mutex and then rearms itself after the mutex has been released), so again the work handler should be prevented from rearming itself in that case..
Finally, there's a potential deadlock in radeon_pm_fini(), because cancel_delayed_work_sync() is called under rdev->pm.mutex, but the work handler tries to acquire the same mutex (if it wins the race).
Fix the issues described above.
Signed-off-by: Rafael J. Wysocki rjw@sisk.pl Reviewed-by: Alex Deucher alexdeucher@gmail.com
drivers/gpu/drm/radeon/radeon.h | 3 +- drivers/gpu/drm/radeon/radeon_pm.c | 41 ++++++++++++++++++++++++++++++------- 2 files changed, 36 insertions(+), 8 deletions(-)
Index: linux-2.6/drivers/gpu/drm/radeon/radeon_pm.c
--- linux-2.6.orig/drivers/gpu/drm/radeon/radeon_pm.c +++ linux-2.6/drivers/gpu/drm/radeon/radeon_pm.c @@ -397,13 +397,20 @@ static ssize_t radeon_set_pm_method(stru rdev->pm.dynpm_planned_action = DYNPM_ACTION_DEFAULT; mutex_unlock(&rdev->pm.mutex); } else if (strncmp("profile", buf, strlen("profile")) == 0) {
- bool flush_wq = false;
mutex_lock(&rdev->pm.mutex);
- rdev->pm.pm_method = PM_METHOD_PROFILE;
- if (rdev->pm.pm_method == PM_METHOD_DYNPM) {
- cancel_delayed_work(&rdev->pm.dynpm_idle_work);
- flush_wq = true;
- }
/* disable dynpm */ rdev->pm.dynpm_state = DYNPM_STATE_DISABLED; rdev->pm.dynpm_planned_action = DYNPM_ACTION_NONE;
- cancel_delayed_work(&rdev->pm.dynpm_idle_work);
- rdev->pm.pm_method = PM_METHOD_PROFILE;
mutex_unlock(&rdev->pm.mutex);
- if (flush_wq)
- flush_workqueue(rdev->wq);
} else { DRM_ERROR("invalid power method!\n"); goto fail; @@ -418,9 +425,18 @@ static DEVICE_ATTR(power_method, S_IRUGO
void radeon_pm_suspend(struct radeon_device *rdev) {
- bool flush_wq = false;
mutex_lock(&rdev->pm.mutex);
- cancel_delayed_work(&rdev->pm.dynpm_idle_work);
- if (rdev->pm.pm_method == PM_METHOD_DYNPM) {
- cancel_delayed_work(&rdev->pm.dynpm_idle_work);
- if (rdev->pm.dynpm_state == DYNPM_STATE_ACTIVE)
- rdev->pm.dynpm_state = DYNPM_STATE_SUSPENDED;
- flush_wq = true;
- }
mutex_unlock(&rdev->pm.mutex);
- if (flush_wq)
- flush_workqueue(rdev->wq);
}
void radeon_pm_resume(struct radeon_device *rdev) @@ -432,6 +448,12 @@ void radeon_pm_resume(struct radeon_devi rdev->pm.current_sclk = rdev->clock.default_sclk; rdev->pm.current_mclk = rdev->clock.default_mclk; rdev->pm.current_vddc = rdev->pm.power_state[rdev->pm.default_power_state_index].clock_info[0].voltage.voltage;
- if (rdev->pm.pm_method == PM_METHOD_DYNPM
- && rdev->pm.dynpm_state == DYNPM_STATE_SUSPENDED) {
- rdev->pm.dynpm_state = DYNPM_STATE_ACTIVE;
- queue_delayed_work(rdev->wq, &rdev->pm.dynpm_idle_work,
- msecs_to_jiffies(RADEON_IDLE_LOOP_MS));
- }
mutex_unlock(&rdev->pm.mutex); radeon_pm_compute_clocks(rdev); } @@ -486,6 +508,8 @@ int radeon_pm_init(struct radeon_device void radeon_pm_fini(struct radeon_device *rdev) { if (rdev->pm.num_power_states > 1) {
- bool flush_wq = false;
mutex_lock(&rdev->pm.mutex); if (rdev->pm.pm_method == PM_METHOD_PROFILE) { rdev->pm.profile = PM_PROFILE_DEFAULT; @@ -493,13 +517,16 @@ void radeon_pm_fini(struct radeon_device radeon_pm_set_clocks(rdev); } else if (rdev->pm.pm_method == PM_METHOD_DYNPM) { /* cancel work */
- cancel_delayed_work_sync(&rdev->pm.dynpm_idle_work);
- cancel_delayed_work(&rdev->pm.dynpm_idle_work);
- flush_wq = true;
/* reset default clocks */ rdev->pm.dynpm_state = DYNPM_STATE_DISABLED; rdev->pm.dynpm_planned_action = DYNPM_ACTION_DEFAULT; radeon_pm_set_clocks(rdev); } mutex_unlock(&rdev->pm.mutex);
- if (flush_wq)
- flush_workqueue(rdev->wq);
device_remove_file(rdev->dev, &dev_attr_power_profile); device_remove_file(rdev->dev, &dev_attr_power_method); @@ -720,12 +747,12 @@ static void radeon_dynpm_idle_work_handl radeon_pm_get_dynpm_state(rdev); radeon_pm_set_clocks(rdev); }
- queue_delayed_work(rdev->wq, &rdev->pm.dynpm_idle_work,
- msecs_to_jiffies(RADEON_IDLE_LOOP_MS));
} mutex_unlock(&rdev->pm.mutex); ttm_bo_unlock_delayed_workqueue(&rdev->mman.bdev, resched);
- queue_delayed_work(rdev->wq, &rdev->pm.dynpm_idle_work,
- msecs_to_jiffies(RADEON_IDLE_LOOP_MS));
}
/* Index: linux-2.6/drivers/gpu/drm/radeon/radeon.h =================================================================== --- linux-2.6.orig/drivers/gpu/drm/radeon/radeon.h +++ linux-2.6/drivers/gpu/drm/radeon/radeon.h @@ -619,7 +619,8 @@ enum radeon_dynpm_state { DYNPM_STATE_DISABLED, DYNPM_STATE_MINIMUM, DYNPM_STATE_PAUSED,
- DYNPM_STATE_ACTIVE
- DYNPM_STATE_ACTIVE,
- DYNPM_STATE_SUSPENDED,
}; enum radeon_dynpm_action { DYNPM_ACTION_NONE, _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel
Probably want to shorten the commit title a bit.
Matt