drm/amdgpu: add option to disable semaphores

Provide module parameter to enable/disable them. Still
enabled by default.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 21 insertions, 1 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 668939a14206..e587e20074d3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -82,6 +82,7 @@ extern int amdgpu_vm_block_size;
 extern int amdgpu_enable_scheduler;
 extern int amdgpu_sched_jobs;
 extern int amdgpu_sched_hw_submission;
+extern int amdgpu_enable_semaphores;
 
 #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS          3000
 #define AMDGPU_MAX_USEC_TIMEOUT                 100000  /* 100 ms */
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 0fcc0bd1622c..adb48353f2e1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -79,6 +79,7 @@ int amdgpu_exp_hw_support = 0;
 int amdgpu_enable_scheduler = 0;
 int amdgpu_sched_jobs = 16;
 int amdgpu_sched_hw_submission = 2;
+int amdgpu_enable_semaphores = 1;
 
 MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing, in megabytes");
 module_param_named(vramlimit, amdgpu_vram_limit, int, 0600);
@@ -152,6 +153,9 @@ module_param_named(sched_jobs, amdgpu_sched_jobs, int, 0444);
 MODULE_PARM_DESC(sched_hw_submission, "the max number of HW submissions (default 2)");
 module_param_named(sched_hw_submission, amdgpu_sched_hw_submission, int, 0444);
 
+MODULE_PARM_DESC(enable_semaphores, "Enable semaphores (1 = enable (default), 0 = disable)");
+module_param_named(enable_semaphores, amdgpu_enable_semaphores, int, 0644);
+
 static struct pci_device_id pciidlist[] = {
 #ifdef CONFIG_DRM_AMDGPU_CIK
         /* Kaveri */
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
index 068aeaff7183..cfd2999acc59 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
@@ -251,6 +251,20 @@ int amdgpu_sync_wait(struct amdgpu_sync *sync)
                 fence_put(e->fence);
                 kfree(e);
         }
+
+        if (amdgpu_enable_semaphores)
+                return 0;
+
+        for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
+                struct amdgpu_fence *fence = sync->sync_to[i];
+                if (!fence)
+                        continue;
+
+                r = fence_wait(&fence->base, false);
+                if (r)
+                        return r;
+        }
+
         return 0;
 }
 
@@ -285,7 +299,8 @@ int amdgpu_sync_rings(struct amdgpu_sync *sync,
                         return -EINVAL;
                 }
 
-                if (amdgpu_enable_scheduler || (count >= AMDGPU_NUM_SYNCS)) {
+                if (amdgpu_enable_scheduler || !amdgpu_enable_semaphores ||
+                    (count >= AMDGPU_NUM_SYNCS)) {
                         /* not enough room, wait manually */
                         r = fence_wait(&fence->base, false);
                         if (r)