Re: [PATCH 03/26] drm/i915/guc: Take engine PM when a context is pinned with GuC submission

John Harrison <john.c.harrison@xxxxxxxxx> · Thu, 7 Oct 2021 11:15:51 -0700

On 10/7/2021 08:19, Matthew Brost wrote:
On Wed, Oct 06, 2021 at 08:45:42PM -0700, John Harrison wrote:
On 10/4/2021 15:06, Matthew Brost wrote:
Taking a PM reference to prevent intel_gt_wait_for_idle from short
circuiting while a scheduling of user context could be enabled.
I'm not sure what 'while a scheduling of user context could be enabled'
means.

Not really sure how this isn't clear.

It means if a user context has scheduling enabled this function cannot
short circuit returning idle.

Matt
Okay. The 'a scheduling' was throwing me off. And I was reading 'could 
be enabled' as saying something that might happen in the future. English 
is great at being ambiguous ;). Maybe 'while any user context has 
scheduling enabled' would be simpler?

John.

  
John.

Returning GT idle when it is not can cause all sorts of issues
throughout the stack.

v2:
   (Daniel Vetter)
    - Add might_lock annotations to pin / unpin function
v3:
   (CI)
    - Drop intel_engine_pm_might_put from unpin path as an async put is
      used
v4:
   (John Harrison)
    - Make intel_engine_pm_might_get/put work with GuC virtual engines
    - Update commit message

Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
   drivers/gpu/drm/i915/gt/intel_context.c       |  2 ++
   drivers/gpu/drm/i915/gt/intel_engine_pm.h     | 32 +++++++++++++++++
   drivers/gpu/drm/i915/gt/intel_gt_pm.h         | 10 ++++++
   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 36 +++++++++++++++++--
   drivers/gpu/drm/i915/intel_wakeref.h          | 12 +++++++
   5 files changed, 89 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 1076066f41e0..f601323b939f 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -240,6 +240,8 @@ int __intel_context_do_pin_ww(struct intel_context *ce,
   	if (err)
   		goto err_post_unpin;
+	intel_engine_pm_might_get(ce->engine);
+
   	if (unlikely(intel_context_is_closed(ce))) {
   		err = -ENOENT;
   		goto err_unlock;
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.h b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
index 6fdeae668e6e..d68675925b79 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
@@ -6,9 +6,11 @@
   #ifndef INTEL_ENGINE_PM_H
   #define INTEL_ENGINE_PM_H
+#include "i915_drv.h"
   #include "i915_request.h"
   #include "intel_engine_types.h"
   #include "intel_wakeref.h"
+#include "intel_gt_pm.h"
   static inline bool
   intel_engine_pm_is_awake(const struct intel_engine_cs *engine)
@@ -31,6 +33,21 @@ static inline bool intel_engine_pm_get_if_awake(struct intel_engine_cs *engine)
   	return intel_wakeref_get_if_active(&engine->wakeref);
   }
+static inline void intel_engine_pm_might_get(struct intel_engine_cs *engine)
+{
+	if (!intel_engine_is_virtual(engine)) {
+		intel_wakeref_might_get(&engine->wakeref);
+	} else {
+		struct intel_gt *gt = engine->gt;
+		struct intel_engine_cs *tengine;
+		intel_engine_mask_t tmp, mask = engine->mask;
+
+		for_each_engine_masked(tengine, gt, mask, tmp)
+			intel_wakeref_might_get(&tengine->wakeref);
+	}
+	intel_gt_pm_might_get(engine->gt);
+}
+
   static inline void intel_engine_pm_put(struct intel_engine_cs *engine)
   {
   	intel_wakeref_put(&engine->wakeref);
@@ -52,6 +69,21 @@ static inline void intel_engine_pm_flush(struct intel_engine_cs *engine)
   	intel_wakeref_unlock_wait(&engine->wakeref);
   }
+static inline void intel_engine_pm_might_put(struct intel_engine_cs *engine)
+{
+	if (!intel_engine_is_virtual(engine)) {
+		intel_wakeref_might_put(&engine->wakeref);
+	} else {
+		struct intel_gt *gt = engine->gt;
+		struct intel_engine_cs *tengine;
+		intel_engine_mask_t tmp, mask = engine->mask;
+
+		for_each_engine_masked(tengine, gt, mask, tmp)
+			intel_wakeref_might_put(&tengine->wakeref);
+	}
+	intel_gt_pm_might_put(engine->gt);
+}
+
   static inline struct i915_request *
   intel_engine_create_kernel_request(struct intel_engine_cs *engine)
   {
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
index 05de6c1af25b..bc898df7a48c 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
@@ -31,6 +31,11 @@ static inline bool intel_gt_pm_get_if_awake(struct intel_gt *gt)
   	return intel_wakeref_get_if_active(&gt->wakeref);
   }
+static inline void intel_gt_pm_might_get(struct intel_gt *gt)
+{
+	intel_wakeref_might_get(&gt->wakeref);
+}
+
   static inline void intel_gt_pm_put(struct intel_gt *gt)
   {
   	intel_wakeref_put(&gt->wakeref);
@@ -41,6 +46,11 @@ static inline void intel_gt_pm_put_async(struct intel_gt *gt)
   	intel_wakeref_put_async(&gt->wakeref);
   }
+static inline void intel_gt_pm_might_put(struct intel_gt *gt)
+{
+	intel_wakeref_might_put(&gt->wakeref);
+}
+
   #define with_intel_gt_pm(gt, tmp) \
   	for (tmp = 1, intel_gt_pm_get(gt); tmp; \
   	     intel_gt_pm_put(gt), tmp = 0)
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 17da2fea1bff..8b82da50c2bc 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1571,7 +1571,12 @@ static int guc_context_pre_pin(struct intel_context *ce,
   static int guc_context_pin(struct intel_context *ce, void *vaddr)
   {
-	return __guc_context_pin(ce, ce->engine, vaddr);
+	int ret = __guc_context_pin(ce, ce->engine, vaddr);
+
+	if (likely(!ret && !intel_context_is_barrier(ce)))
+		intel_engine_pm_get(ce->engine);
+
+	return ret;
   }
   static void guc_context_unpin(struct intel_context *ce)
@@ -1580,6 +1585,9 @@ static void guc_context_unpin(struct intel_context *ce)
   	unpin_guc_id(guc, ce);
   	lrc_unpin(ce);
+
+	if (likely(!intel_context_is_barrier(ce)))
+		intel_engine_pm_put_async(ce->engine);
   }
   static void guc_context_post_unpin(struct intel_context *ce)
@@ -2341,8 +2349,30 @@ static int guc_virtual_context_pre_pin(struct intel_context *ce,
   static int guc_virtual_context_pin(struct intel_context *ce, void *vaddr)
   {
   	struct intel_engine_cs *engine = guc_virtual_get_sibling(ce->engine, 0);
+	int ret = __guc_context_pin(ce, engine, vaddr);
+	intel_engine_mask_t tmp, mask = ce->engine->mask;
+
+	if (likely(!ret))
+		for_each_engine_masked(engine, ce->engine->gt, mask, tmp)
+			intel_engine_pm_get(engine);
-	return __guc_context_pin(ce, engine, vaddr);
+	return ret;
+}
+
+static void guc_virtual_context_unpin(struct intel_context *ce)
+{
+	intel_engine_mask_t tmp, mask = ce->engine->mask;
+	struct intel_engine_cs *engine;
+	struct intel_guc *guc = ce_to_guc(ce);
+
+	GEM_BUG_ON(context_enabled(ce));
+	GEM_BUG_ON(intel_context_is_barrier(ce));
+
+	unpin_guc_id(guc, ce);
+	lrc_unpin(ce);
+
+	for_each_engine_masked(engine, ce->engine->gt, mask, tmp)
+		intel_engine_pm_put_async(engine);
   }
   static void guc_virtual_context_enter(struct intel_context *ce)
@@ -2379,7 +2409,7 @@ static const struct intel_context_ops virtual_guc_context_ops = {
   	.pre_pin = guc_virtual_context_pre_pin,
   	.pin = guc_virtual_context_pin,
-	.unpin = guc_context_unpin,
+	.unpin = guc_virtual_context_unpin,
   	.post_unpin = guc_context_post_unpin,
   	.ban = guc_context_ban,
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index 545c8f277c46..4f4c2e15e736 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -123,6 +123,12 @@ enum {
   	__INTEL_WAKEREF_PUT_LAST_BIT__
   };
+static inline void
+intel_wakeref_might_get(struct intel_wakeref *wf)
+{
+	might_lock(&wf->mutex);
+}
+
   /**
    * intel_wakeref_put_flags: Release the wakeref
    * @wf: the wakeref
@@ -170,6 +176,12 @@ intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay)
   			    FIELD_PREP(INTEL_WAKEREF_PUT_DELAY, delay));
   }
+static inline void
+intel_wakeref_might_put(struct intel_wakeref *wf)
+{
+	might_lock(&wf->mutex);
+}
+
   /**
    * intel_wakeref_lock: Lock the wakeref (mutex)
    * @wf: the wakeref







