drm/i915/guc: Add stall timer to non blocking CTB send function

Implement a stall timer which fails H2G CTBs once a period of time
with no forward progress is reached to prevent deadlock.

v2:
 (Michal)
  - Improve error message in ct_deadlock()
  - Set broken when ct_deadlock() returns true
  - Return -EPIPE on ct_deadlock()
v3:
 (Michal)
  - Add ms to stall timer comment
 (Matthew)
  - Move broken check to intel_guc_ct_send()

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210708162055.129996-6-matthew.brost@intel.com

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
index 5bb8bef024c8..bee03794c1eb 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h
@@ -9,6 +9,7 @@
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
+#include <linux/ktime.h>
 
 #include "intel_guc_fwif.h"
 
@@ -68,6 +69,9 @@ struct intel_guc_ct {
 		struct list_head incoming; /* incoming requests */
 		struct work_struct worker; /* handler for incoming requests */
 	} requests;
+
+	/** @stall_time: time of first time a CTB submission is stalled */
+	ktime_t stall_time;
 };
 
 void intel_guc_ct_init_early(struct intel_guc_ct *ct);