drm/radeon: disable power control on hybrid laptops

Windows 10 (and some 8.1) systems use standardized
ACPI calls for hybrid laptops to control dGPU power.
Detect those cases and disable the AMD specific ATPX
power control.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_atpx_handler.c

@@ -182,6 +182,11 @@ static int radeon_atpx_validate(struct radeon_atpx *atpx)
 				  ATPX_DFP_SIGNAL_MUXED))
 			atpx->functions.disp_mux_cntl = true;
 
+		if (valid_bits & ATPX_MS_HYBRID_GFX_SUPPORTED) {
+			printk("Hybrid Graphics, ATPX dGPU power cntl disabled\n");
+			atpx->functions.power_cntl = false;
+		}
+
 		kfree(info);
 	}
 	return 0;