drm/amdgpu: Add amdgpu_gfx_off_ctrl function

v2:
   1. drop the special handling for the hw IP
      suggested by hawking and Christian.
   2. refine the variable name suggested by Flora.

This funciton as the entry of gfx off feature.
we arbitrat gfx off feature enable/disable in this
function.
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -950,6 +950,10 @@ struct amdgpu_gfx {
 	/* NGG */
 	struct amdgpu_ngg		ngg;
 
+	/* gfx off */
+	bool                            gfx_off_state; /* true: enabled, false: disabled */
+	struct mutex                    gfx_off_mutex;
+	uint32_t                        gfx_off_req_count; /* default 1, enable gfx off: dec 1, disable gfx off: add 1 */
 	/* pipe reservation */
 	struct mutex			pipe_reserve_mutex;
 	DECLARE_BITMAP			(pipe_reserve_bitmap, AMDGPU_MAX_COMPUTE_QUEUES);
@@ -1774,6 +1778,7 @@ void amdgpu_device_program_register_sequence(struct amdgpu_device *adev,
 					     const u32 array_size);
 
 bool amdgpu_device_is_px(struct drm_device *dev);
+void amdgpu_gfx_off_ctrl(struct amdgpu_device *adev, bool enable);
 /* atpx handler */
 #if defined(CONFIG_VGA_SWITCHEROO)
 void amdgpu_register_atpx_handler(void);

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -2367,6 +2367,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->gfx.gpu_clock_mutex);
 	mutex_init(&adev->srbm_mutex);
 	mutex_init(&adev->gfx.pipe_reserve_mutex);
+	mutex_init(&adev->gfx.gfx_off_mutex);
 	mutex_init(&adev->grbm_idx_mutex);
 	mutex_init(&adev->mn_lock);
 	mutex_init(&adev->virt.vf_errors.lock);
@@ -2394,6 +2395,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	INIT_DELAYED_WORK(&adev->late_init_work,
 			  amdgpu_device_ip_late_init_func_handler);
 
+	adev->gfx.gfx_off_req_count = 1;
 	adev->pm.ac_power = power_supply_is_system_supplied() > 0 ? true : false;
 
 	/* Registers mapping */

drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c

@@ -340,3 +340,39 @@ void amdgpu_gfx_compute_mqd_sw_fini(struct amdgpu_device *adev)
 			      &ring->mqd_gpu_addr,
 			      &ring->mqd_ptr);
 }
+
+/* amdgpu_gfx_off_ctrl - Handle gfx off feature enable/disable
+ *
+ * @adev: amdgpu_device pointer
+ * @bool enable true: enable gfx off feature, false: disable gfx off feature
+ *
+ * 1. gfx off feature will be enabled by gfx ip after gfx cg gp enabled.
+ * 2. other client can send request to disable gfx off feature, the request should be honored.
+ * 3. other client can cancel their request of disable gfx off feature
+ * 4. other client should not send request to enable gfx off feature before disable gfx off feature.
+ */
+
+void amdgpu_gfx_off_ctrl(struct amdgpu_device *adev, bool enable)
+{
+	if (!(adev->powerplay.pp_feature & PP_GFXOFF_MASK))
+		return;
+
+	if (!adev->powerplay.pp_funcs->set_powergating_by_smu)
+		return;
+
+	mutex_lock(&adev->gfx.gfx_off_mutex);
+
+	if (!enable)
+		adev->gfx.gfx_off_req_count++;
+	else if (adev->gfx.gfx_off_req_count > 0)
+		adev->gfx.gfx_off_req_count--;
+
+	if (enable && !adev->gfx.gfx_off_state && !adev->gfx.gfx_off_req_count) {
+		if (!amdgpu_dpm_set_powergating_by_smu(adev, AMD_IP_BLOCK_TYPE_GFX, true))
+			adev->gfx.gfx_off_state = true;
+	} else if (!enable && adev->gfx.gfx_off_state) {
+		if (!amdgpu_dpm_set_powergating_by_smu(adev, AMD_IP_BLOCK_TYPE_GFX, false))
+			adev->gfx.gfx_off_state = false;
+	}
+	mutex_unlock(&adev->gfx.gfx_off_mutex);
+}