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 | 13 ++++++++----- drivers/video/am335x-fb.h | 9 +++++++-- 2 files changed, 15 insertions(+), 7 deletions(-)
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 */ };