[patch] fix driver hang when vt switch with rotation

[Hong Liu]

The rotate memory buffer is allocated by TTM now, the mem->offset may be changed
after rebinding during VT switch.
This causes driver hang after switching back to X server.

Thanks,
Hong

diff --git a/src/i830_driver.c b/src/i830_driver.c
index 854e377..5976ed8 100644
--- a/src/i830_driver.c
+++ b/src/i830_driver.c
@@ -3205,6 +3205,17 @@ I830EnterVT(int scrnIndex, int flags)
 	output->funcs->dpms(output, DPMSModeOff);
    }
 
+   for (o = 0; o < config->num_crtc; o++) {
+       xf86CrtcPtr crtc = config->crtc[o];
+
+       if (crtc->rotatedPixmap || crtc->rotatedData) {
+	   crtc->funcs->shadow_destroy(crtc, crtc->rotatedPixmap,
+		   			crtc->rotatedData);
+	   crtc->rotatedPixmap = NULL;
+	   crtc->rotatedData = NULL;
+       }
+   }
+
    if (!xf86SetDesiredModes (pScrn))
       return FALSE;