gma500: Fix oaktrail probing part 1

The Oaktrail platform does not use the GCT/VBT format that is used by the
Moorestowm (non PC legacy) equivalent device. It uses the BIOS tables which
means an opregion and the like.

The current code uses the wrong table which breaks things like the Fujitsu
q550 tablets. Fix the table usage as a first step.

The problem was found and diagnosed by Chia-I Wu
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/mid_bios.c

@@ -142,6 +142,12 @@ static void mid_get_vbt_data(struct drm_psb_private *dev_priv)
 	memcpy(vbt, vbt_virtual, sizeof(*vbt));
 	iounmap(vbt_virtual); /* Free virtual address space */
 
+	/* No matching signature don't process the data */
+	if (memcmp(vbt->signature, "$GCT", 4)) {
+		vbt->size = 0;
+		return;
+	}
+
 	dev_dbg(dev->dev, "GCT revision is %x\n", vbt->revision);
 
 	switch (vbt->revision) {

drivers/gpu/drm/gma500/oaktrail_device.c

@@ -29,6 +29,7 @@
 #include <asm/mrst.h>
 #include <asm/intel_scu_ipc.h>
 #include "mid_bios.h"
+#include "intel_bios.h"
 
 static int oaktrail_output_init(struct drm_device *dev)
 {
@@ -456,9 +457,24 @@ static int oaktrail_power_up(struct drm_device *dev)
 }
 
 
+static void oaktrail_chip_setup(struct drm_device *dev)
+{
+	int ret = mid_chip_setup(dev);
+	if (ret < 0)
+		return ret;
+	if (vbt->size == 0) {
+		/* Now pull the BIOS data */
+		gma_intel_opregion_init(dev);
+		psb_intel_init_bios(dev);
+	}
+	return 0;
+}
+
 static void oaktrail_teardown(struct drm_device *dev)
 {
 	oaktrail_hdmi_teardown(dev);
+	if (vbt->size == 0)
+		psb_intel_destroy_bios(dev);
 }
 
 const struct psb_ops oaktrail_chip_ops = {
@@ -468,7 +484,7 @@ const struct psb_ops oaktrail_chip_ops = {
 	.crtcs = 2,
 	.sgx_offset = MRST_SGX_OFFSET,
 
-	.chip_setup = mid_chip_setup,
+	.chip_setup = oaktrail_chip_setup,
 	.chip_teardown = oaktrail_teardown,
 	.crtc_helper = &oaktrail_helper_funcs,
 	.crtc_funcs = &psb_intel_crtc_funcs,