drm/radeon/kms: detect sideport memory on IGP chips

This detects if the sideport memory is enabled and
if it is VRAM is evicted on suspend/resume.

This should fix s/r issues on some IGPs.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/rs400.c b/drivers/gpu/drm/radeon/rs400.c
index 368415d..bf7b3cf 100644
--- a/drivers/gpu/drm/radeon/rs400.c
+++ b/drivers/gpu/drm/radeon/rs400.c
@@ -356,6 +356,7 @@
 	rdev->mc.vram_location = G_00015C_MC_FB_START(tmp) << 16;
 	rdev->mc.gtt_location = 0xFFFFFFFFUL;
 	r = radeon_mc_setup(rdev);
+	rdev->mc.igp_sideport_enabled = radeon_combios_sideport_present(rdev);
 	if (r)
 		return r;
 	return 0;