drm/vmwgfx: Filter out modes those cannot be supported by the current VRAM size.

commit 9a72384d upstream.

When screen objects are enabled, the bpp is assumed to be 32, otherwise
it is set to 16.

v2:
* Use u32 instead of u64 for assumed_bpp.
* Fixed mechanism to check for screen objects
* Limit the back buffer size to VRAM.
Signed-off-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
[bwh: Backported to 3.2: drop changes for dev_priv->prim_bb_mem]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -1826,6 +1826,14 @@ int vmw_du_connector_fill_modes(struct drm_connector *connector,
 		DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_PVSYNC)
 	};
 	int i;
+	u32 assumed_bpp = 2;
+
+	/*
+	 * If using screen objects, then assume 32-bpp because that's what the
+	 * SVGA device is assuming
+	 */
+	if (dev_priv->sou_priv)
+		assumed_bpp = 4;
 
 	/* Add preferred mode */
 	{
@@ -1836,8 +1844,9 @@ int vmw_du_connector_fill_modes(struct drm_connector *connector,
 		mode->vdisplay = du->pref_height;
 		vmw_guess_mode_timing(mode);
 
-		if (vmw_kms_validate_mode_vram(dev_priv, mode->hdisplay * 2,
-					       mode->vdisplay)) {
+		if (vmw_kms_validate_mode_vram(dev_priv,
+						mode->hdisplay * assumed_bpp,
+						mode->vdisplay)) {
 			drm_mode_probed_add(connector, mode);
 		} else {
 			drm_mode_destroy(dev, mode);
@@ -1859,7 +1868,8 @@ int vmw_du_connector_fill_modes(struct drm_connector *connector,
 		    bmode->vdisplay > max_height)
 			continue;
 
-		if (!vmw_kms_validate_mode_vram(dev_priv, bmode->hdisplay * 2,
+		if (!vmw_kms_validate_mode_vram(dev_priv,
+						bmode->hdisplay * assumed_bpp,
 						bmode->vdisplay))
 			continue;