[PATCH 1/7 V2] drm/amd/amdgpu: Simplify SDMA reset mechanism by removing dynamic callbacks

[jesse.zhang at amd.com]

From: "Jesse.zhang at amd.com" <jesse.zhang at amd.com>

Since KFD no longer registers its own callbacks for SDMA resets, and only KGD uses the reset mechanism,
we can simplify the SDMA reset flow by directly calling the ring's `stop_queue` and `start_queue` functions.
This patch removes the dynamic callback mechanism and prepares for its eventual deprecation.

1. **Remove Dynamic Callbacks**:
   - The `pre_reset` and `post_reset` callback invocations in `amdgpu_sdma_reset_engine` are removed.
   - Instead, the ring's `stop_queue` and `start_queue` functions are called directly during the reset process.

2. **Prepare for Deprecation of Dynamic Mechanism**:
   - By removing the callback invocations, this patch prepares the codebase for the eventual removal of the dynamic callback registration mechanism.

Signed-off-by: Jesse Zhang <Jesse.Zhang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h |  2 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c | 34 +++---------------------
 drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c |  2 ++
 3 files changed, 8 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index 615c3d5c5a8d..1b66be2b49dc 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -237,6 +237,8 @@ struct amdgpu_ring_funcs {
 	void (*patch_ce)(struct amdgpu_ring *ring, unsigned offset);
 	void (*patch_de)(struct amdgpu_ring *ring, unsigned offset);
 	int (*reset)(struct amdgpu_ring *ring, unsigned int vmid);
+	int (*stop_queue)(struct amdgpu_device *adev, uint32_t instance_id);
+	int (*start_queue)(struct amdgpu_device *adev, uint32_t instance_id);
 	void (*emit_cleaner_shader)(struct amdgpu_ring *ring);
 	bool (*is_guilty)(struct amdgpu_ring *ring);
 };
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
index 0a9893fee828..7d862c887a1a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
@@ -558,16 +558,10 @@ void amdgpu_sdma_register_on_reset_callbacks(struct amdgpu_device *adev, struct
  * @adev: Pointer to the AMDGPU device
  * @instance_id: ID of the SDMA engine instance to reset
  *
- * This function performs the following steps:
- * 1. Calls all registered pre_reset callbacks to allow KFD and AMDGPU to save their state.
- * 2. Resets the specified SDMA engine instance.
- * 3. Calls all registered post_reset callbacks to allow KFD and AMDGPU to restore their state.
- *
  * Returns: 0 on success, or a negative error code on failure.
  */
 int amdgpu_sdma_reset_engine(struct amdgpu_device *adev, uint32_t instance_id)
 {
-	struct sdma_on_reset_funcs *funcs;
 	int ret = 0;
 	struct amdgpu_sdma_instance *sdma_instance = &adev->sdma.instance[instance_id];
 	struct amdgpu_ring *gfx_ring = &sdma_instance->ring;
@@ -589,18 +583,8 @@ int amdgpu_sdma_reset_engine(struct amdgpu_device *adev, uint32_t instance_id)
 		page_sched_stopped = true;
 	}
 
-	/* Invoke all registered pre_reset callbacks */
-	list_for_each_entry(funcs, &adev->sdma.reset_callback_list, list) {
-		if (funcs->pre_reset) {
-			ret = funcs->pre_reset(adev, instance_id);
-			if (ret) {
-				dev_err(adev->dev,
-				"beforeReset callback failed for instance %u: %d\n",
-					instance_id, ret);
-				goto exit;
-			}
-		}
-	}
+	if (gfx_ring->funcs->stop_queue)
+		gfx_ring->funcs->stop_queue(adev, instance_id);
 
 	/* Perform the SDMA reset for the specified instance */
 	ret = amdgpu_dpm_reset_sdma(adev, 1 << instance_id);
@@ -609,18 +593,8 @@ int amdgpu_sdma_reset_engine(struct amdgpu_device *adev, uint32_t instance_id)
 		goto exit;
 	}
 
-	/* Invoke all registered post_reset callbacks */
-	list_for_each_entry(funcs, &adev->sdma.reset_callback_list, list) {
-		if (funcs->post_reset) {
-			ret = funcs->post_reset(adev, instance_id);
-			if (ret) {
-				dev_err(adev->dev,
-				"afterReset callback failed for instance %u: %d\n",
-					instance_id, ret);
-				goto exit;
-			}
-		}
-	}
+	if (gfx_ring->funcs->start_queue)
+		gfx_ring->funcs->start_queue(adev, instance_id);
 
 exit:
 	/* Restart the scheduler's work queue for the GFX and page rings
diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c b/drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c
index 688a720bbbbd..df82a97a5388 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c
@@ -2143,6 +2143,8 @@ static const struct amdgpu_ring_funcs sdma_v4_4_2_ring_funcs = {
 	.emit_reg_wait = sdma_v4_4_2_ring_emit_reg_wait,
 	.emit_reg_write_reg_wait = amdgpu_ring_emit_reg_write_reg_wait_helper,
 	.reset = sdma_v4_4_2_reset_queue,
+	.stop_queue = sdma_v4_4_2_stop_queue,
+	.start_queue = sdma_v4_4_2_restore_queue,
 	.is_guilty = sdma_v4_4_2_ring_is_guilty,
 };
 
-- 
2.25.1