From 3b4e16eb530aa3eaa29535a7d511c105c0de963a Mon Sep 17 00:00:00 2001 From: Hannes Petermaier Date: Tue, 3 Feb 2015 13:22:23 +0100 Subject: [PATCH] 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 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 ms within panel-settings, called "pon_delay" Signed-off-by: Hannes Petermaier --- 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 ab9894102d..6f956499d7 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 8a0b131495..7f799d1f31 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 */ }; -- 2.30.2