[PATCH 2/2] drm/i915/guc: Don't disable a context whose enable is still pending

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

Various processes involve requesting GuC to disable a given context.
However context enable/disable is an asynchronous process in the GuC.
Thus, it is possible the previous enable request is still being
processed when the disable request is triggered. Having both enable
and disable in flight concurrently is illegal - GuC will return an
error and fail the second operation. The KMD side handler for the
completion message also can't cope with having both pending flags set.
So delay the disable request until it is safe to send.

Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 31 +++++++++++++++----
 1 file changed, 25 insertions(+), 6 deletions(-)

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 d399e4d238c10..8c34b0a5abf9a 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -3150,7 +3150,8 @@ guc_context_revoke(struct intel_context *ce, struct i915_request *rq,
 		guc_cancel_context_requests(ce);
 		intel_engine_signal_breadcrumbs(ce->engine);
 	} else if (!context_pending_disable(ce)) {
-		u16 guc_id;
+		u16 guc_id = ~0;
+		bool pending_enable = context_pending_enable(ce);
 
 		/*
 		 * We add +2 here as the schedule disable complete CTB handler
@@ -3158,7 +3159,11 @@ guc_context_revoke(struct intel_context *ce, struct i915_request *rq,
 		 */
 		atomic_add(2, &ce->pin_count);
 
-		guc_id = prep_context_pending_disable(ce);
+		if (pending_enable)
+			guc_id = ce->guc_id.id;
+		else
+			guc_id = prep_context_pending_disable(ce);
+
 		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 
 		/*
@@ -3169,7 +3174,15 @@ guc_context_revoke(struct intel_context *ce, struct i915_request *rq,
 		with_intel_runtime_pm(runtime_pm, wakeref) {
 			__guc_context_set_preemption_timeout(guc, guc_id,
 							     preempt_timeout_ms);
-			__guc_context_sched_disable(guc, ce, guc_id);
+			if (!pending_enable)
+				__guc_context_sched_disable(guc, ce, guc_id);
+		}
+
+		if (pending_enable) {
+			/* Can't have both in flight concurrently, so try again later... */
+			mod_delayed_work(system_unbound_wq,
+					 &ce->guc_state.sched_disable_delay_work,
+					 msecs_to_jiffies(1));
 		}
 	} else {
 		if (!context_guc_id_invalid(ce))
@@ -3222,7 +3235,13 @@ static void __delay_sched_disable(struct work_struct *wrk)
 
 	spin_lock_irqsave(&ce->guc_state.lock, flags);
 
-	if (bypass_sched_disable(guc, ce)) {
+	if (context_pending_enable(ce)) {
+		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+		/* Can't have both in flight concurrently, so try again later... */
+		mod_delayed_work(system_unbound_wq,
+				 &ce->guc_state.sched_disable_delay_work,
+				 msecs_to_jiffies(1));
+	} else if (bypass_sched_disable(guc, ce)) {
 		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 		intel_context_sched_disable_unpin(ce);
 	} else {
@@ -3257,8 +3276,8 @@ static void guc_context_sched_disable(struct intel_context *ce)
 	if (bypass_sched_disable(guc, ce)) {
 		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 		intel_context_sched_disable_unpin(ce);
-	} else if (!intel_context_is_closed(ce) && !guc_id_pressure(guc, ce) &&
-		   delay) {
+	} else if ((!intel_context_is_closed(ce) && !guc_id_pressure(guc, ce) &&
+		    delay) || context_pending_enable(ce)) {
 		spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 		mod_delayed_work(system_unbound_wq,
 				 &ce->guc_state.sched_disable_delay_work,
-- 
2.41.0