drm/i915/guc: Add a second client, to be used for preemption

This second client is created with priority KMD_HIGH, and marked
as preemptive. This will allow us to request preemption using GuC actions.

v2: Extract clients creation into a helper, debugfs fixups. (Michał)
Recreate doorbell on init. (Daniele)
Move clients into an array.

v3: And move clients back from an array, to get rid of the enum (Michał)

v4: Use is_high_priority, move DRM_ERROR into __create_doorbell, move
GEM_BUG_ON inside guc_clients_create (Michał)

v5: Split the BUG_ON (Michał)

v6: Cleanup after error during doorbell reinit (Michał)

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Jeff McGee <jeff.mcgee@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026141737.31656-1-michal.winiarski@intel.com

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 34862aa8f9c0bc1ec1d07c4d7456e3c2db8032e5..c1e5bba91bff879025491d27386065dca9fd535b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2484,6 +2484,8 @@ static int i915_guc_info(struct seq_file *m, void *data)
 
        seq_printf(m, "\nGuC execbuf client @ %p:\n", guc->execbuf_client);
        i915_guc_client_info(m, dev_priv, guc->execbuf_client);
+       seq_printf(m, "\nGuC preempt client @ %p:\n", guc->preempt_client);
+       i915_guc_client_info(m, dev_priv, guc->preempt_client);
 
        i915_guc_log_info(m, dev_priv);
 

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index d1a5613da24c6139d9866c622ced8b9e09680c71..b0f034f924319d7a33bfb2be08299fede9d853f6 100644 (file)
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -33,10 +33,11 @@
  *
  * GuC client:
  * A i915_guc_client refers to a submission path through GuC. Currently, there
- * is only one of these (the execbuf_client) and this one is charged with all
- * submissions to the GuC. This struct is the owner of a doorbell, a process
- * descriptor and a workqueue (all of them inside a single gem object that
- * contains all required pages for these elements).
+ * are two clients. One of them (the execbuf_client) is charged with all
+ * submissions to the GuC, the other one (preempt_client) is responsible for
+ * preempting the execbuf_client. This struct is the owner of a doorbell, a
+ * process descriptor and a workqueue (all of them inside a single gem object
+ * that contains all required pages for these elements).
  *
  * GuC stage descriptor:
  * During initialization, the driver allocates a static pool of 1024 such
@@ -83,7 +84,8 @@
 
 static inline bool is_high_priority(struct i915_guc_client* client)
 {
-       return client->priority <= GUC_CLIENT_PRIORITY_HIGH;
+       return (client->priority == GUC_CLIENT_PRIORITY_KMD_HIGH ||
+               client->priority == GUC_CLIENT_PRIORITY_HIGH);
 }
 
 static int __reserve_doorbell(struct i915_guc_client *client)
@@ -196,8 +198,11 @@ static int __create_doorbell(struct i915_guc_client *client)
        doorbell->cookie = 0;
 
        err = __guc_allocate_doorbell(client->guc, client->stage_id);
-       if (err)
+       if (err) {
                doorbell->db_status = GUC_DOORBELL_DISABLED;
+               DRM_ERROR("Couldn't create client %u doorbell: %d\n",
+                         client->stage_id, err);
+       }
 
        return err;
 }
@@ -363,6 +368,8 @@ static void guc_stage_desc_init(struct intel_guc *guc,
        memset(desc, 0, sizeof(*desc));
 
        desc->attribute = GUC_STAGE_DESC_ATTR_ACTIVE | GUC_STAGE_DESC_ATTR_KERNEL;
+       if (is_high_priority(client))
+               desc->attribute |= GUC_STAGE_DESC_ATTR_PREEMPT;
        desc->stage_id = client->stage_id;
        desc->priority = client->priority;
        desc->db_id = client->doorbell_id;
@@ -763,14 +770,14 @@ static int guc_init_doorbell_hw(struct intel_guc *guc)
 
        /* Now for every client (and not only execbuf_client) make sure their
         * doorbells are known by the GuC */
-       //for (client = client_list; client != NULL; client = client->next)
-       {
-               ret = __create_doorbell(client);
-               if (ret) {
-                       DRM_ERROR("Couldn't recreate client %u doorbell: %d\n",
-                               client->stage_id, ret);
-                       return ret;
-               }
+       ret = __create_doorbell(guc->execbuf_client);
+       if (ret)
+               return ret;
+
+       ret = __create_doorbell(guc->preempt_client);
+       if (ret) {
+               __destroy_doorbell(guc->execbuf_client);
+               return ret;
        }
 
        /* Read back & verify all (used & unused) doorbell registers */
@@ -895,6 +902,50 @@ static void guc_client_free(struct i915_guc_client *client)
        kfree(client);
 }
 
+static int guc_clients_create(struct intel_guc *guc)
+{
+       struct drm_i915_private *dev_priv = guc_to_i915(guc);
+       struct i915_guc_client *client;
+
+       GEM_BUG_ON(guc->execbuf_client);
+       GEM_BUG_ON(guc->preempt_client);
+
+       client = guc_client_alloc(dev_priv,
+                                 INTEL_INFO(dev_priv)->ring_mask,
+                                 GUC_CLIENT_PRIORITY_KMD_NORMAL,
+                                 dev_priv->kernel_context);
+       if (IS_ERR(client)) {
+               DRM_ERROR("Failed to create GuC client for submission!\n");
+               return PTR_ERR(client);
+       }
+       guc->execbuf_client = client;
+
+       client = guc_client_alloc(dev_priv,
+                                 INTEL_INFO(dev_priv)->ring_mask,
+                                 GUC_CLIENT_PRIORITY_KMD_HIGH,
+                                 dev_priv->preempt_context);
+       if (IS_ERR(client)) {
+               DRM_ERROR("Failed to create GuC client for preemption!\n");
+               guc_client_free(guc->execbuf_client);
+               guc->execbuf_client = NULL;
+               return PTR_ERR(client);
+       }
+       guc->preempt_client = client;
+
+       return 0;
+}
+
+static void guc_clients_destroy(struct intel_guc *guc)
+{
+       struct i915_guc_client *client;
+
+       client = fetch_and_zero(&guc->execbuf_client);
+       guc_client_free(client);
+
+       client = fetch_and_zero(&guc->preempt_client);
+       guc_client_free(client);
+}
+
 static void guc_policy_init(struct guc_policy *policy)
 {
        policy->execution_quantum = POLICY_DEFAULT_EXECUTION_QUANTUM_US;
@@ -1134,7 +1185,6 @@ static void i915_guc_submission_unpark(struct intel_engine_cs *engine)
 int i915_guc_submission_enable(struct drm_i915_private *dev_priv)
 {
        struct intel_guc *guc = &dev_priv->guc;
-       struct i915_guc_client *client = guc->execbuf_client;
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        int err;
@@ -1152,28 +1202,28 @@ int i915_guc_submission_enable(struct drm_i915_private *dev_priv)
                     sizeof(struct guc_wq_item) *
                     I915_NUM_ENGINES > GUC_WQ_SIZE);
 
-       if (!client) {
-               client = guc_client_alloc(dev_priv,
-                                         INTEL_INFO(dev_priv)->ring_mask,
-                                         GUC_CLIENT_PRIORITY_KMD_NORMAL,
-                                         dev_priv->kernel_context);
-               if (IS_ERR(client)) {
-                       DRM_ERROR("Failed to create GuC client for execbuf!\n");
-                       return PTR_ERR(client);
-               }
-
-               guc->execbuf_client = client;
+       /*
+        * We're being called on both module initialization and on reset,
+        * until this flow is changed, we're using regular client presence to
+        * determine which case are we in, and whether we should allocate new
+        * clients or just reset their workqueues.
+        */
+       if (!guc->execbuf_client) {
+               err = guc_clients_create(guc);
+               if (err)
+                       return err;
+       } else {
+               guc_reset_wq(guc->execbuf_client);
+               guc_reset_wq(guc->preempt_client);
        }
 
        err = intel_guc_sample_forcewake(guc);
        if (err)
-               goto err_execbuf_client;
-
-       guc_reset_wq(client);
+               goto err_free_clients;
 
        err = guc_init_doorbell_hw(guc);
        if (err)
-               goto err_execbuf_client;
+               goto err_free_clients;
 
        /* Take over from manual control of ELSP (execlists) */
        guc_interrupts_capture(dev_priv);
@@ -1187,9 +1237,8 @@ int i915_guc_submission_enable(struct drm_i915_private *dev_priv)
 
        return 0;
 
-err_execbuf_client:
-       guc_client_free(guc->execbuf_client);
-       guc->execbuf_client = NULL;
+err_free_clients:
+       guc_clients_destroy(guc);
        return err;
 }
 
@@ -1204,6 +1253,5 @@ void i915_guc_submission_disable(struct drm_i915_private *dev_priv)
        /* Revert back to manual ELSP submission */
        intel_engines_reset_default_submission(dev_priv);
 
-       guc_client_free(guc->execbuf_client);
-       guc->execbuf_client = NULL;
+       guc_clients_destroy(guc);
 }

diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index aa1583167b0ac8b180fb229037a505d3a6228b31..6ca55c5bed3c2d6d8a8e4d08ace7bac5a9ccf413 100644 (file)
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -58,6 +58,7 @@ struct intel_guc {
        void *shared_data_vaddr;
 
        struct i915_guc_client *execbuf_client;
+       struct i915_guc_client *preempt_client;
 
        DECLARE_BITMAP(doorbell_bitmap, GUC_NUM_DOORBELLS);
        /* Cyclic counter mod pagesize  */