drivers/video/am335x-fb: Add possibility to wait for stable power/picture

Often on boards exists a circuit which switches power on/off to LCD display.
Due to the need of limiting the in-rush current the output voltage from this
circuit rises "slowly", so it is necessary to wait a bit (VCC ramp up time)
before starting output on LCD-pins.
This time is specified in <n> ms within the panel-settings, called "pup_delay"

Further some LCDs need a couple of frames to stabilize the image on it.
We have now the possibility to wait some time after starting output on LCD.
This time is also specified in <n> ms within panel-settings, called "pon_delay"

Signed-off-by: Hannes Petermaier <oe5hpm@oevsv.at>

drivers/video/am335x-fb.c

@@ -127,6 +127,12 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
 	memset((void *)gd->fb_base, 0, 0x20);
 	*(unsigned int *)gd->fb_base = 0x4000;
 
+	/* turn ON display through powercontrol function if accessible */
+	if (0 != panel->panel_power_ctrl)
+		panel->panel_power_ctrl(1);
+
+	debug("am335x-fb: wait for stable power ...\n");
+	mdelay(panel->pup_delay);
 	lcdhw->clkc_enable = LCD_CORECLKEN | LCD_LIDDCLKEN | LCD_DMACLKEN;
 	lcdhw->raster_ctrl = 0;
 	lcdhw->ctrl = LCD_CLK_DIVISOR(panel->pxl_clk_div) | LCD_RASTER_MODE;
@@ -159,11 +165,8 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
 
 	gd->fb_base += 0x20;	/* point fb behind palette */
 
-	/* turn ON display through powercontrol function if accessible */
-	if (0 != panel->panel_power_ctrl) {
-		mdelay(panel->pon_delay);
-		panel->panel_power_ctrl(1);
-	}
+	debug("am335x-fb: waiting picture to be stable.\n.");
+	mdelay(panel->pon_delay);
 
 	return 0;
 }

drivers/video/am335x-fb.h

@@ -55,9 +55,14 @@ struct am335x_lcdpanel {
 	unsigned int	vsw;		/* Vertical Sync Pulse Width */
 	unsigned int	pxl_clk_div;	/* Pixel clock divider*/
 	unsigned int	pol;		/* polarity of sync, clock signals */
+	unsigned int	pup_delay;	/*
+					 * time in ms after power on to
+					 * initialization of lcd-controller
+					 * (VCC ramp up time)
+					 */
 	unsigned int	pon_delay;	/*
-					 * time in ms for turning on lcd after
-					 * initializing lcd-controller
+					 * time in ms after initialization of
+					 * lcd-controller (pic stabilization)
 					 */
 	void (*panel_power_ctrl)(int);	/* fp for power on/off display */
 };