From: Akash Goel <akash.g...@intel.com>

With the addition of new Host2GuC actions related to GuC logging, there
is a need of a lock to serialize them, as they can execute concurrently
with each other and also with other existing actions.

v2: Use mutex in place of spinlock to serialize, as sleep can happen
    while waiting for the action's response from GuC. (Tvrtko)

v3: To conform to the general rules, acquire mutex before taking the
    forcewake. (Tvrtko)

Signed-off-by: Akash Goel <akash.g...@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c | 3 +++
 drivers/gpu/drm/i915/intel_guc.h           | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c 
b/drivers/gpu/drm/i915/i915_guc_submission.c
index 2cdc3ca..04b2e87 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -87,6 +87,7 @@ static int host2guc_action(struct intel_guc *guc, u32 *data, 
u32 len)
        if (WARN_ON(len < 1 || len > 15))
                return -EINVAL;
 
+       mutex_lock(&guc->action_lock);
        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
 
        dev_priv->guc.action_count += 1;
@@ -125,6 +126,7 @@ static int host2guc_action(struct intel_guc *guc, u32 
*data, u32 len)
        dev_priv->guc.action_status = status;
 
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+       mutex_unlock(&guc->action_lock);
 
        return ret;
 }
@@ -1365,6 +1367,7 @@ int i915_guc_submission_init(struct drm_i915_private 
*dev_priv)
 
        guc->ctx_pool_vma = vma;
        ida_init(&guc->ctx_ids);
+       mutex_init(&guc->action_lock);
        guc_log_create(guc);
        guc_addon_create(guc);
 
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index e7999dd..907d13a 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -157,6 +157,9 @@ struct intel_guc {
 
        uint64_t submissions[I915_NUM_ENGINES];
        uint32_t last_seqno[I915_NUM_ENGINES];
+
+       /* To serialize the Host2GuC actions */
+       struct mutex action_lock;
 };
 
 /* intel_guc_loader.c */
-- 
1.9.2

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