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Commit ae6c4574 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Force the switch to the i915->kernel_context 



In the next few patches, we will have a hard requirement that we emit a
context-switch to the perma-pinned i915->kernel_context (so that we can
save the HW state using that context-switch). As the first context
itself may be classed as a kernel context, we want to be explicit in our
comparison. For an extra-layer of finesse, we can check the last
unretired context on the engine; as well as the last retired context
when idle.

v2: verbose verbosity
v3: Always force the switch, even when the engine is idle, and update
the assert that this happens before suspend.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> #v1
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171110142634.10551-2-chris@chris-wilson.co.uk
parent 1803fcbc

drivers/gpu/drm/i915/i915_gem.c

+6 −4
Original line number Diff line number Diff line
@@ -4693,14 +4693,16 @@ void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj) 
		i915_gem_object_put(obj);

}



static void assert_kernel_context_is_current(struct drm_i915_private *dev_priv)

static void assert_kernel_context_is_current(struct drm_i915_private *i915)

{

	struct i915_gem_context *kernel_context = i915->kernel_context;

	struct intel_engine_cs *engine;

	enum intel_engine_id id;



	for_each_engine(engine, dev_priv, id)

		GEM_BUG_ON(engine->last_retired_context &&

			   !i915_gem_context_is_kernel(engine->last_retired_context));

	for_each_engine(engine, i915, id) {

		GEM_BUG_ON(__i915_gem_active_peek(&engine->timeline->last_request));

		GEM_BUG_ON(engine->last_retired_context != kernel_context);

	}

}



void i915_gem_sanitize(struct drm_i915_private *i915)

drivers/gpu/drm/i915/intel_engine_cs.c

+24 −2
Original line number Diff line number Diff line
@@ -1596,10 +1596,32 @@ bool intel_engines_are_idle(struct drm_i915_private *dev_priv) 
	return true;

}



/**

 * intel_engine_has_kernel_context:

 * @engine: the engine

 *

 * Returns true if the last context to be executed on this engine, or has been

 * executed if the engine is already idle, is the kernel context

 * (#i915.kernel_context).

 */

bool intel_engine_has_kernel_context(const struct intel_engine_cs *engine)

{

	return (!engine->last_retired_context ||

		i915_gem_context_is_kernel(engine->last_retired_context));

	const struct i915_gem_context * const kernel_context =

		engine->i915->kernel_context;

	struct drm_i915_gem_request *rq;



	lockdep_assert_held(&engine->i915->drm.struct_mutex);



	/*

	 * Check the last context seen by the engine. If active, it will be

	 * the last request that remains in the timeline. When idle, it is

	 * the last executed context as tracked by retirement.

	 */

	rq = __i915_gem_active_peek(&engine->timeline->last_request);

	if (rq)

		return rq->ctx == kernel_context;

	else

		return engine->last_retired_context == kernel_context;

}



void intel_engines_reset_default_submission(struct drm_i915_private *i915)