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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>
utp
Hannes Petermaier 2015-02-03 13:22:23 +01:00 committed by Tom Rini
parent 5822f5ae7f
commit 3b4e16eb53
2 changed files with 15 additions and 7 deletions
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13
drivers/video/am335x-fb.c
View File

@ -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;
}

9
drivers/video/am335x-fb.h
View File

@ -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 */
};