drm/amdgpu: Implement a new userqueue fence driver

Developed a userqueue fence driver for the userqueue process shared
BO synchronization.

Create a dma fence having write pointer as the seqno and allocate a
seq64 memory for each user queue process and feed this memory address
into the firmware/hardware, thus the firmware writes the read pointer
into the given address when the process completes it execution.
Compare wptr and rptr, if rptr >= wptr, signal the fences for the waiting
process to consume the buffers.

v2: Worked on review comments from Christian for the following
    modifications

    - Add wptr as sequence number into the fence
    - Add a reference count for the fence driver
    - Add dma_fence_put below the list_del as it might
      frees the userq fence.
    - Trim unnecessary code in interrupt handler.
    - Check dma fence signaled state in dma fence creation
      function for a potential problem of hardware completing
      the job processing beforehand.
    - Add necessary locks.
    - Create a list and process all the unsignaled fences.
    - clean up fences in destroy function.
    - implement .signaled callback function

v3: Worked on review comments from Christian
    - Modify naming convention for reference counted objects
    - Fix fence driver reference drop issue
    - Drop amdgpu_userq_fence_driver_process() function return value

v4: Worked on review comments from Christian
    - Moved fence driver allocation into amdgpu_userq_fence_driver_alloc()
    - Added detail doc mentioning the differences b/w
      two spinlocks declared.

v5: Worked on review comments from Christian
    - Check before upcast and remove local variable
    - Add error handling in fence_drv alloc function.
    - Move rptr read fn outside of the loop and remove WARN_ON in
      destroy function.

v6:
  - clear the seq64 memory in user fence driver(Christian)
  - fix for the wptr va bo mapping(Christian)
  - move the fence_drv xa entry erase code from the interrupt handler
    into user fence destroy function

Signed-off-by: Arunpravin Paneer Selvam <[email protected]>
Reviewed-by: Christian König <[email protected]>
Suggested-by: Christian König <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index dd2ec890d186..0221e7928989 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -52,6 +52,7 @@
 #include "amdgpu_sched.h"
 #include "amdgpu_xgmi.h"
 #include "amdgpu_userqueue.h"
+#include "amdgpu_userq_fence.h"
 #include "../amdxcp/amdgpu_xcp_drv.h"
 
 /*
@@ -3039,6 +3040,10 @@ static int __init amdgpu_init(void)
 	if (r)
 		goto error_fence;
 
+	r = amdgpu_userq_fence_slab_init();
+	if (r)
+		goto error_fence;
+
 	DRM_INFO("amdgpu kernel modesetting enabled.\n");
 	amdgpu_register_atpx_handler();
 	amdgpu_acpi_detect();
@@ -3070,6 +3075,7 @@ static void __exit amdgpu_exit(void)
 	amdgpu_acpi_release();
 	amdgpu_sync_fini();
 	amdgpu_fence_slab_fini();
+	amdgpu_userq_fence_slab_fini();
 	mmu_notifier_synchronize();
 	amdgpu_xcp_drv_release();
 }