[PATCH next, v2] kernel: Add 1 ms delay to init handler to fix s3 resume hang

[Zhenneng Li]

This is a workaround for s3 resume hang for r7 340(amdgpu).
When we test s3 with r7 340 on arm64 platform, graphics card will hang up,
the error message are as follows:
Mar  4 01:14:11 greatwall-GW-XXXXXX-XXX kernel: [    1.599374][ 7] [  T291] amdgpu 0000:02:00.0: fb0: amdgpudrmfb frame buffer device
Mar  4 01:14:11 greatwall-GW-XXXXXX-XXX kernel: [    1.612869][ 7] [  T291] [drm:amdgpu_device_ip_late_init [amdgpu]] *ERROR* late_init of IP block <si_dpm> failed -22
Mar  4 01:14:11 greatwall-GW-XXXXXX-XXX kernel: [    1.623392][ 7] [  T291] amdgpu 0000:02:00.0: amdgpu_device_ip_late_init failed
Mar  4 01:14:11 greatwall-GW-XXXXXX-XXX kernel: [    1.630696][ 7] [  T291] amdgpu 0000:02:00.0: Fatal error during GPU init
Mar  4 01:14:11 greatwall-GW-XXXXXX-XXX kernel: [    1.637477][ 7] [  T291] [drm] amdgpu: finishing device.

On the following hardware:
lspci -nn -s 05:00.0
05:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Oland [Radeon HD 8570 / R7 240/340 / Radeon 520 OEM] [1002:6611] (rev 87)

Signed-off-by: Zhenneng Li <lizhenneng at kylinos.cn>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 3987ecb24ef4..1eced991b5b2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -2903,6 +2903,8 @@ static void amdgpu_device_delayed_init_work_handler(struct work_struct *work)
 		container_of(work, struct amdgpu_device, delayed_init_work.work);
 	int r;
 
+	mdelay(1);
+
 	r = amdgpu_ib_ring_tests(adev);
 	if (r)
 		DRM_ERROR("ib ring test failed (%d).\n", r);
-- 
2.25.1