[RFC] drm/amd/display: Add and use new dm_prepare_suspend() callback

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello at amd.com>

The displays currently don't get turned off until after other IP blocks
have been suspended.  However turning off the displays first gives a
visible response that the system is on it's way down.

Turn off displays in a prepare_suspend() callback instead.

Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 21 ++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 70594e9179e8c..320b3ba74baea 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3037,6 +3037,21 @@ static void hpd_rx_irq_work_suspend(struct amdgpu_display_manager *dm)
 	}
 }
 
+static int dm_prepare_suspend(struct amdgpu_ip_block *ip_block)
+{
+	struct amdgpu_device *adev = ip_block->adev;
+
+	if (amdgpu_in_reset(adev))
+		return 0;
+
+	WARN_ON(adev->dm.cached_state);
+	adev->dm.cached_state = drm_atomic_helper_suspend(adev_to_drm(adev));
+	if (IS_ERR(adev->dm.cached_state))
+		return PTR_ERR(adev->dm.cached_state);
+
+	return 0;
+}
+
 static int dm_suspend(struct amdgpu_ip_block *ip_block)
 {
 	struct amdgpu_device *adev = ip_block->adev;
@@ -3067,11 +3082,6 @@ static int dm_suspend(struct amdgpu_ip_block *ip_block)
 		return 0;
 	}
 
-	WARN_ON(adev->dm.cached_state);
-	adev->dm.cached_state = drm_atomic_helper_suspend(adev_to_drm(adev));
-	if (IS_ERR(adev->dm.cached_state))
-		return PTR_ERR(adev->dm.cached_state);
-
 	s3_handle_hdmi_cec(adev_to_drm(adev), true);
 
 	s3_handle_mst(adev_to_drm(adev), true);
@@ -3468,6 +3478,7 @@ static const struct amd_ip_funcs amdgpu_dm_funcs = {
 	.early_fini = amdgpu_dm_early_fini,
 	.hw_init = dm_hw_init,
 	.hw_fini = dm_hw_fini,
+	.prepare_suspend = dm_prepare_suspend,
 	.suspend = dm_suspend,
 	.resume = dm_resume,
 	.is_idle = dm_is_idle,
-- 
2.43.0