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>

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

drivers/gpu/drm/radeon/r600.c

@@ -340,6 +340,10 @@ static void r600_mc_resume(struct radeon_device *rdev)
 	WREG32(D1VGA_CONTROL, d1vga_control);
 	WREG32(D2VGA_CONTROL, d2vga_control);
 	WREG32(VGA_RENDER_CONTROL, vga_render_control);
+
+	/* we need to own VRAM, so turn off the VGA renderer here
+	 * to stop it overwriting our objects */
+	radeon_avivo_vga_render_disable(rdev);
 }
 
 int r600_mc_init(struct radeon_device *rdev)

drivers/gpu/drm/radeon/rs600.c

@@ -28,6 +28,7 @@
 #include "drmP.h"
 #include "radeon_reg.h"
 #include "radeon.h"
+#include "avivod.h"
 
 #include "rs600_reg_safe.h"
 
@@ -197,6 +198,8 @@ void rs600_mc_disable_clients(struct radeon_device *rdev)
 		       "programming pipes. Bad things might happen.\n");
 	}
 
+	radeon_avivo_vga_render_disable(rdev);
+
 	tmp = RREG32(AVIVO_D1VGA_CONTROL);
 	WREG32(AVIVO_D1VGA_CONTROL, tmp & ~AVIVO_DVGA_CONTROL_MODE_ENABLE);
 	tmp = RREG32(AVIVO_D2VGA_CONTROL);

drivers/gpu/drm/radeon/rv770.c

@@ -229,6 +229,10 @@ static void rv770_mc_resume(struct radeon_device *rdev)
 	WREG32(D1VGA_CONTROL, d1vga_control);
 	WREG32(D2VGA_CONTROL, d2vga_control);
 	WREG32(VGA_RENDER_CONTROL, vga_render_control);
+
+	/* we need to own VRAM, so turn off the VGA renderer here
+	 * to stop it overwriting our objects */
+	radeon_avivo_vga_render_disable(rdev);
 }