drm/amdgpu: update comments about s0ix suspend/resume

Provide and explanation as to why we skip GFX and PSP for
S0ix.  GFX goes into gfxoff, same as runtime, so no need
to tear down and re-init.  PSP is part of the always on
state, so no need to touch it.
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2737,10 +2737,14 @@ static int amdgpu_device_ip_suspend_phase2(struct amdgpu_device *adev)
 			continue;
 		}
 
-		/* XXX fix these remaining cases */
+		/* skip suspend of gfx and psp for S0ix
+		 * gfx is in gfxoff state, so on resume it will exit gfxoff just
+		 * like at runtime. PSP is also part of the always on hardware
+		 * so no need to suspend it.
+		 */
 		if (adev->in_s0ix &&
-		    (adev->ip_blocks[i].version->type == AMD_IP_BLOCK_TYPE_PSP || /* breaks resume */
-		     adev->ip_blocks[i].version->type == AMD_IP_BLOCK_TYPE_GFX))  /* breaks suspend */
+		    (adev->ip_blocks[i].version->type == AMD_IP_BLOCK_TYPE_PSP ||
+		     adev->ip_blocks[i].version->type == AMD_IP_BLOCK_TYPE_GFX))
 			continue;
 
 		/* XXX handle errors */