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drm/i915: Enable i915_gem_wait_for_idle() without holding struct_mutex

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The principal motivation for this was to try and eliminate the
struct_mutex from i915_gem_suspend - but we still need to hold the mutex
current for the i915_gem_context_lost(). (The issue there is that there
may be an indirect lockdep cycle between cpu_hotplug (i.e. suspend) and
struct_mutex via the stop_machine().) For the moment, enabling last
request tracking for the engine, allows us to do busyness checking and
waiting without requiring the struct_mutex - which is useful in its own
right.

As a side-effect of having a robust means for tracking engine busyness,
we can replace our other busyness heuristic, that of comparing against
the last submitted seqno. For paranoid reasons, we have a semi-ordered
check of that seqno inside the hangchecker, which we can now improve to
an ordered check of the engine's busyness (removing a locked xchg in the
process).

v2: Pass along "bool interruptible" as being unlocked we cannot rely on
i915->mm.interruptible being stable or even under our control.
v3: Replace check Ironlake i915_gpu_busy() with the common precalculated value

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-6-git-send-email-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2016-08-05 10:14:11 +01:00
parent 90f4fcd56b
commit dcff85c844
13 changed files with 68 additions and 76 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/gpu/drm/i915/intel_ringbuffer.h
View File

@ -3,6 +3,7 @@
#include <linux/hashtable.h>
#include "i915_gem_batch_pool.h"
#include "i915_gem_request.h"
#define I915_CMD_HASH_ORDER 9
@ -307,6 +308,13 @@ struct intel_engine_cs {
*/
u32 last_submitted_seqno;
/* An RCU guarded pointer to the last request. No reference is
* held to the request, users must carefully acquire a reference to
* the request using i915_gem_active_get_request_rcu(), or hold the
* struct_mutex.
*/
struct i915_gem_active last_request;
struct i915_gem_context *last_context;
struct intel_engine_hangcheck hangcheck;
@ -465,7 +473,6 @@ static inline u32 intel_ring_offset(struct intel_ring *ring, u32 value)
int __intel_ring_space(int head, int tail, int size);
void intel_ring_update_space(struct intel_ring *ring);
int __must_check intel_engine_idle(struct intel_engine_cs *engine);
void intel_engine_init_seqno(struct intel_engine_cs *engine, u32 seqno);
int intel_init_pipe_control(struct intel_engine_cs *engine, int size);
@ -475,6 +482,14 @@ void intel_engine_setup_common(struct intel_engine_cs *engine);
int intel_engine_init_common(struct intel_engine_cs *engine);
void intel_engine_cleanup_common(struct intel_engine_cs *engine);
static inline int intel_engine_idle(struct intel_engine_cs *engine,
bool interruptible)
{
/* Wait upon the last request to be completed */
return i915_gem_active_wait_unlocked(&engine->last_request,
interruptible, NULL, NULL);
}
int intel_init_render_ring_buffer(struct intel_engine_cs *engine);
int intel_init_bsd_ring_buffer(struct intel_engine_cs *engine);
int intel_init_bsd2_ring_buffer(struct intel_engine_cs *engine);
@ -504,17 +519,6 @@ static inline u32 intel_hws_seqno_address(struct intel_engine_cs *engine)
}
/* intel_breadcrumbs.c -- user interrupt bottom-half for waiters */
struct intel_wait {
struct rb_node node;
struct task_struct *tsk;
u32 seqno;
};
struct intel_signal_node {
struct rb_node node;
struct intel_wait wait;
};
int intel_engine_init_breadcrumbs(struct intel_engine_cs *engine);
static inline void intel_wait_init(struct intel_wait *wait, u32 seqno)
@ -561,4 +565,9 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine);
unsigned int intel_kick_waiters(struct drm_i915_private *i915);
unsigned int intel_kick_signalers(struct drm_i915_private *i915);
static inline bool intel_engine_is_active(struct intel_engine_cs *engine)
{
return i915_gem_active_isset(&engine->last_request);
}
#endif /* _INTEL_RINGBUFFER_H_ */