sm501fb: Ensure panel interface is not tristated when setup

When we setup the panel interface whilst configuring the
framebuffer, we should ensure the panel interface is not
in tristate, in case the bootloader or previous setup has
not enabled it.
Signed-off-by: NBen Dooks <ben-linux@fluff.org>
Signed-off-by: NAntonino Daplas <adaplas@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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;

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)