drm/radeon/kms: Check module arguments to be valid V2

This patch add a function which check module argument to be
valid. On invalid argument it prints a warning and setback
the default value.

V2: Allow 0 for vram limit & agp mode which are the default
value
Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_device.c

@@ -546,9 +546,72 @@ void radeon_agp_disable(struct radeon_device *rdev)
 	}
 }
 
-/*
- * Radeon device.
- */
+void radeon_check_arguments(struct radeon_device *rdev)
+{
+	/* vramlimit must be a power of two */
+	switch (radeon_vram_limit) {
+	case 0:
+	case 4:
+	case 8:
+	case 16:
+	case 32:
+	case 64:
+	case 128:
+	case 256:
+	case 512:
+	case 1024:
+	case 2048:
+	case 4096:
+		break;
+	default:
+		dev_warn(rdev->dev, "vram limit (%d) must be a power of 2\n",
+				radeon_vram_limit);
+		radeon_vram_limit = 0;
+		break;
+	}
+	radeon_vram_limit = radeon_vram_limit << 20;
+	/* gtt size must be power of two and greater or equal to 32M */
+	switch (radeon_gart_size) {
+	case 4:
+	case 8:
+	case 16:
+		dev_warn(rdev->dev, "gart size (%d) too small forcing to 512M\n",
+				radeon_gart_size);
+		radeon_gart_size = 512;
+		break;
+	case 32:
+	case 64:
+	case 128:
+	case 256:
+	case 512:
+	case 1024:
+	case 2048:
+	case 4096:
+		break;
+	default:
+		dev_warn(rdev->dev, "gart size (%d) must be a power of 2\n",
+				radeon_gart_size);
+		radeon_gart_size = 512;
+		break;
+	}
+	rdev->mc.gtt_size = radeon_gart_size * 1024 * 1024;
+	/* AGP mode can only be -1, 1, 2, 4, 8 */
+	switch (radeon_agpmode) {
+	case -1:
+	case 0:
+	case 1:
+	case 2:
+	case 4:
+	case 8:
+		break;
+	default:
+		dev_warn(rdev->dev, "invalid AGP mode %d (valid mode: "
+				"-1, 0, 1, 2, 4, 8)\n", radeon_agpmode);
+		radeon_agpmode = 0;
+		break;
+	}
+}
+
 int radeon_device_init(struct radeon_device *rdev,
 		       struct drm_device *ddev,
 		       struct pci_dev *pdev,
@@ -587,9 +650,9 @@ int radeon_device_init(struct radeon_device *rdev,
 
 	/* Set asic functions */
 	r = radeon_asic_init(rdev);
-	if (r) {
+	if (r)
 		return r;
-	}
+	radeon_check_arguments(rdev);
 
 	if (rdev->flags & RADEON_IS_AGP && radeon_agpmode == -1) {
 		radeon_agp_disable(rdev);