drm/radeon: don't touch DCE or VGA regs on Hainan (v3)

Hainan has no display hardware:
- no DCE (crtc, uniphy, dac, etc.)
- no VGA

v2: fix bios fetch
v3: fix interrupts

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon_bios.c b/drivers/gpu/drm/radeon/radeon_bios.c
index b801591..9448cbf 100644
--- a/drivers/gpu/drm/radeon/radeon_bios.c
+++ b/drivers/gpu/drm/radeon/radeon_bios.c
@@ -221,24 +221,28 @@
 
 	/* enable the rom */
 	WREG32(R600_BUS_CNTL, (bus_cntl & ~R600_BIOS_ROM_DIS));
-	/* Disable VGA mode */
-	WREG32(AVIVO_D1VGA_CONTROL,
-	       (d1vga_control & ~(AVIVO_DVGA_CONTROL_MODE_ENABLE |
-		AVIVO_DVGA_CONTROL_TIMING_SELECT)));
-	WREG32(AVIVO_D2VGA_CONTROL,
-	       (d2vga_control & ~(AVIVO_DVGA_CONTROL_MODE_ENABLE |
-		AVIVO_DVGA_CONTROL_TIMING_SELECT)));
-	WREG32(AVIVO_VGA_RENDER_CONTROL,
-	       (vga_render_control & ~AVIVO_VGA_VSTATUS_CNTL_MASK));
+	if (!ASIC_IS_NODCE(rdev)) {
+		/* Disable VGA mode */
+		WREG32(AVIVO_D1VGA_CONTROL,
+		       (d1vga_control & ~(AVIVO_DVGA_CONTROL_MODE_ENABLE |
+					  AVIVO_DVGA_CONTROL_TIMING_SELECT)));
+		WREG32(AVIVO_D2VGA_CONTROL,
+		       (d2vga_control & ~(AVIVO_DVGA_CONTROL_MODE_ENABLE |
+					  AVIVO_DVGA_CONTROL_TIMING_SELECT)));
+		WREG32(AVIVO_VGA_RENDER_CONTROL,
+		       (vga_render_control & ~AVIVO_VGA_VSTATUS_CNTL_MASK));
+	}
 	WREG32(R600_ROM_CNTL, rom_cntl | R600_SCK_OVERWRITE);
 
 	r = radeon_read_bios(rdev);
 
 	/* restore regs */
 	WREG32(R600_BUS_CNTL, bus_cntl);
-	WREG32(AVIVO_D1VGA_CONTROL, d1vga_control);
-	WREG32(AVIVO_D2VGA_CONTROL, d2vga_control);
-	WREG32(AVIVO_VGA_RENDER_CONTROL, vga_render_control);
+	if (!ASIC_IS_NODCE(rdev)) {
+		WREG32(AVIVO_D1VGA_CONTROL, d1vga_control);
+		WREG32(AVIVO_D2VGA_CONTROL, d2vga_control);
+		WREG32(AVIVO_VGA_RENDER_CONTROL, vga_render_control);
+	}
 	WREG32(R600_ROM_CNTL, rom_cntl);
 	return r;
 }