drm/amd:Enable/Disable NBPSTATE on On/OFF of UVD

We observe black lines (underflow) on display when playing a
4K video with UVD. On Disabling Low memory P state this issue is
not seen.
In this patch ,disabling low memory P state only when video
size >= 4k.
Multiple runs of power measurement shows no impact

Signed-off-by: suresh guttula <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/nospec.h>
+#include "hwmgr.h"
+#define WIDTH_4K 3840
 
 static int amdgpu_debugfs_pm_init(struct amdgpu_device *adev);
 
···
 		mutex_lock(&adev->pm.mutex);
 		amdgpu_dpm_set_powergating_by_smu(adev, AMD_IP_BLOCK_TYPE_UVD, !enable);
 		mutex_unlock(&adev->pm.mutex);
+	}
+	/* enable/disable Low Memory PState for UVD (4k videos) */
+	if (adev->asic_type == CHIP_STONEY &&
+		adev->uvd.decode_image_width >= WIDTH_4K) {
+		struct pp_hwmgr *hwmgr = adev->powerplay.pp_handle;
+
+		if (hwmgr && hwmgr->hwmgr_func &&
+		    hwmgr->hwmgr_func->update_nbdpm_pstate)
+			hwmgr->hwmgr_func->update_nbdpm_pstate(hwmgr,
+							       !enable,
+							       true);
 	}
 }
 

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

···
 	buf_sizes[0x1] = dpb_size;
 	buf_sizes[0x2] = image_size;
 	buf_sizes[0x4] = min_ctx_size;
+	/* store image width to adjust nb memory pstate */
+	adev->uvd.decode_image_width = width;
 	return 0;
 }
 

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

···
 	struct drm_sched_entity entity;
 	struct delayed_work	idle_work;
 	unsigned		harvest_config;
+	/* store image width to adjust nb memory state */
+	unsigned		decode_image_width;
 };
 
 int amdgpu_uvd_sw_init(struct amdgpu_device *adev);