drm/radeon/kms: disable VGA rendering engine before taking over VRAM

Before we use any of VRAM, we need to disable the VGA rendering
engine, this render text mode into a graphical framebuffer
for scanout, however it does this on vblank, and can end up
overwriting the GART table and r600 shader objects.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/avivod.h b/drivers/gpu/drm/radeon/avivod.h
index d4e6e6e4a938..e2b92c445bab 100644
--- a/drivers/gpu/drm/radeon/avivod.h
+++ b/drivers/gpu/drm/radeon/avivod.h
@@ -57,4 +57,13 @@
 #define VGA_RENDER_CONTROL                              0x0300
 #define         VGA_VSTATUS_CNTL_MASK                           0x00030000
 
+/* AVIVO disable VGA rendering */
+static inline void radeon_avivo_vga_render_disable(struct radeon_device *rdev)
+{
+        u32 vga_render;
+        vga_render = RREG32(VGA_RENDER_CONTROL);
+        vga_render &= ~VGA_VSTATUS_CNTL_MASK;
+        WREG32(VGA_RENDER_CONTROL, vga_render);
+}
+
 #endif