diff mbox

[U-Boot,v2,01/24] drivers/video/am335x-fb: Add possibility to wait for stable power/picture

Message ID 1422966166-3973-1-git-send-email-oe5hpm@oevsv.at
State Accepted
Delegated to: Tom Rini
Headers show

Commit Message

Hannes Schmelzer Feb. 3, 2015, 12:22 p.m. UTC 
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>

---
Changes for V2: None
---
 drivers/video/am335x-fb.c |   13 ++++++++-----
 drivers/video/am335x-fb.h |    9 +++++++--
 2 files changed, 15 insertions(+), 7 deletions(-)

Comments

Tom Rini March 6, 2015, 3:44 p.m. UTC | #1 
On Tue, Feb 03, 2015 at 01:22:23PM +0100, Hannes Petermaier wrote:

> 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>

Applied to u-boot/master, thanks!
diff mbox

Patch

diff --git a/drivers/video/am335x-fb.c b/drivers/video/am335x-fb.c
index ab98941..6f95649 100644
--- a/drivers/video/am335x-fb.c
+++ b/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;
 }
diff --git a/drivers/video/am335x-fb.h b/drivers/video/am335x-fb.h
index 8a0b131..7f799d1 100644
--- a/drivers/video/am335x-fb.h
+++ b/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 */
 };