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Commit 780f262a authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Replace wait-on-mutex with wait-on-bit in reset worker 



Since we have a cooperative mode now with a direct reset, we can avoid
the contention on struct_mutex and instead try then sleep on the
I915_RESET_IN_PROGRESS bit. If the mutex is held and that bit is
cleared, all is fine. Otherwise, we sleep for a bit and try again. In
the worst case we sleep for an extra second waiting for the mutex to be
released (no one touching the GPU is allowed the struct_mutex whilst the
I915_RESET_IN_PROGRESS bit is set). But when we have a direct reset,
this allows us to clean up the reset worker faster.

v2: Remember to call wake_up_bit() after changing (for the faster wakeup
as promised)

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-12-chris@chris-wilson.co.uk
parent 221fe799

drivers/gpu/drm/i915/i915_drv.c

+8 −6
Original line number Diff line number Diff line
@@ -1726,8 +1726,8 @@ int i915_resume_switcheroo(struct drm_device *dev) 
 * i915_reset - reset chip after a hang

 * @dev: drm device to reset

 *

 * Reset the chip.  Useful if a hang is detected. Returns zero on successful

 * reset or otherwise an error code.

 * Reset the chip.  Useful if a hang is detected. Marks the device as wedged

 * on failure.

 *

 * Caller must hold the struct_mutex.

 *
@@ -1739,7 +1739,7 @@ int i915_resume_switcheroo(struct drm_device *dev) 
 *   - re-init interrupt state

 *   - re-init display

 */

int i915_reset(struct drm_i915_private *dev_priv)

void i915_reset(struct drm_i915_private *dev_priv)

{

	struct drm_device *dev = &dev_priv->drm;

	struct i915_gpu_error *error = &dev_priv->gpu_error;
@@ -1748,7 +1748,7 @@ int i915_reset(struct drm_i915_private *dev_priv) 
	lockdep_assert_held(&dev->struct_mutex);



	if (!test_and_clear_bit(I915_RESET_IN_PROGRESS, &error->flags))

		return test_bit(I915_WEDGED, &error->flags) ? -EIO : 0;

		return;



	/* Clear any previous failed attempts at recovery. Time to try again. */

	__clear_bit(I915_WEDGED, &error->flags);
@@ -1798,11 +1798,13 @@ int i915_reset(struct drm_i915_private *dev_priv) 
	intel_sanitize_gt_powersave(dev_priv);

	intel_autoenable_gt_powersave(dev_priv);



	return 0;

wakeup:

	wake_up_bit(&error->flags, I915_RESET_IN_PROGRESS);

	return;



error:

	set_bit(I915_WEDGED, &error->flags);

	return ret;

	goto wakeup;

}



static int i915_pm_suspend(struct device *kdev)

drivers/gpu/drm/i915/i915_drv.h

+1 −1
Original line number Diff line number Diff line
@@ -2884,7 +2884,7 @@ extern long i915_compat_ioctl(struct file *filp, unsigned int cmd, 
#endif

extern int intel_gpu_reset(struct drm_i915_private *dev_priv, u32 engine_mask);

extern bool intel_has_gpu_reset(struct drm_i915_private *dev_priv);

extern int i915_reset(struct drm_i915_private *dev_priv);

extern void i915_reset(struct drm_i915_private *dev_priv);

extern int intel_guc_reset(struct drm_i915_private *dev_priv);

extern void intel_engine_init_hangcheck(struct intel_engine_cs *engine);

extern unsigned long i915_chipset_val(struct drm_i915_private *dev_priv);

drivers/gpu/drm/i915/i915_irq.c

+18 −13
Original line number Diff line number Diff line
@@ -2497,7 +2497,6 @@ static void i915_reset_and_wakeup(struct drm_i915_private *dev_priv) 
	char *error_event[] = { I915_ERROR_UEVENT "=1", NULL };

	char *reset_event[] = { I915_RESET_UEVENT "=1", NULL };

	char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL };

	int ret;



	kobject_uevent_env(kobj, KOBJ_CHANGE, error_event);
@@ -2512,24 +2511,30 @@ static void i915_reset_and_wakeup(struct drm_i915_private *dev_priv) 
	 * simulated reset via debugs, so get an RPM reference.

	 */

	intel_runtime_pm_get(dev_priv);



	intel_prepare_reset(dev_priv);



	do {

		/*

		 * All state reset _must_ be completed before we update the

		 * reset counter, for otherwise waiters might miss the reset

		 * pending state and not properly drop locks, resulting in

		 * deadlocks with the reset work.

		 */

	mutex_lock(&dev_priv->drm.struct_mutex);

	ret = i915_reset(dev_priv);

		if (mutex_trylock(&dev_priv->drm.struct_mutex)) {

			i915_reset(dev_priv);

			mutex_unlock(&dev_priv->drm.struct_mutex);

		}



	intel_finish_reset(dev_priv);

		/* We need to wait for anyone holding the lock to wakeup */

	} while (wait_on_bit_timeout(&dev_priv->gpu_error.flags,

				     I915_RESET_IN_PROGRESS,

				     TASK_UNINTERRUPTIBLE,

				     HZ));



	intel_finish_reset(dev_priv);

	intel_runtime_pm_put(dev_priv);



	if (ret == 0)

	if (!test_bit(I915_WEDGED, &dev_priv->gpu_error.flags))

		kobject_uevent_env(kobj,

				   KOBJ_CHANGE, reset_done_event);