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;
 
 
 /* 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)