diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c
index d97edd7a6e415949384f5f216905fe45cc557017..1be95a68d69678d4ba05400bedd506467826cb99 100644
--- a/drivers/video/sm501fb.c
+++ b/drivers/video/sm501fb.c
@@ -777,6 +777,11 @@ static int sm501fb_set_par_pnl(struct fb_info *info)
 	writel(control, fbi->regs + SM501_DC_PANEL_CONTROL);
 	sm501fb_sync_regs(fbi);
 
+	/* ensure the panel interface is not tristated at this point */
+
+	sm501_modify_reg(fbi->dev->parent, SM501_SYSTEM_CONTROL,
+			 0, SM501_SYSCTRL_PANEL_TRISTATE);
+
 	/* power the panel up */
 	sm501fb_panel_power(fbi, 1);
 	return 0;
diff --git a/include/linux/sm501-regs.h b/include/linux/sm501-regs.h
index 014e73b31fc0ce92005f39c3bb00542c371729d8..df7620dd8f3181133e6818a062cd85347c5e084d 100644
--- a/include/linux/sm501-regs.h
+++ b/include/linux/sm501-regs.h
@@ -15,6 +15,24 @@
 
 /* config 1 */
 #define SM501_SYSTEM_CONTROL 		(0x000000)
+
+#define SM501_SYSCTRL_PANEL_TRISTATE	(1<<0)
+#define SM501_SYSCTRL_MEM_TRISTATE	(1<<1)
+#define SM501_SYSCTRL_CRT_TRISTATE	(1<<2)
+
+#define SM501_SYSCTRL_PCI_SLAVE_BURST_MASK (3<<4)
+#define SM501_SYSCTRL_PCI_SLAVE_BURST_1	(0<<4)
+#define SM501_SYSCTRL_PCI_SLAVE_BURST_2	(1<<4)
+#define SM501_SYSCTRL_PCI_SLAVE_BURST_4	(2<<4)
+#define SM501_SYSCTRL_PCI_SLAVE_BURST_8	(3<<4)
+
+#define SM501_SYSCTRL_PCI_CLOCK_RUN_EN	(1<<6)
+#define SM501_SYSCTRL_PCI_RETRY_DISABLE	(1<<7)
+#define SM501_SYSCTRL_PCI_SUBSYS_LOCK	(1<<11)
+#define SM501_SYSCTRL_PCI_BURST_READ_EN	(1<<15)
+
+/* miscellaneous control */
+
 #define SM501_MISC_CONTROL		(0x000004)
 
 #define SM501_MISC_BUS_SH		(0x0)