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Queries: LCD interfacing with OMAP3530

Other Parts Discussed in Thread: OMAP3530

Dear All,

We are using OMAP3530 processor for one of our project & we facing some issues regarding LCD interfacing.

Please find all the details & issues bellow

Processor                      : OMAP3530
Development board     : Beagleboard Rev C4
OS                                 : Linux
Kernel Ver                     : 2.6.32
Rootfs distribution        : Angstrom with X11
LCD panel                      : 5" 800x480 (datasheet attached)
LCD interface                : 24 RGB
LCD interface board      : Customized
LCD pixel clock              : 30 Mhz (typical)

            
I have registered the LCD panel to dss device with following timings signals as given in LCD datasheet

.x_res = 800,
.y_res = 480,

.pixel_clock = 30000,

.hsw     = 48,
.hfp      = 40,
.hbp     = 80,

.vsw    = 3,
.vfp     = 13,
.vbp    = 32,


Now the issue is when I boot my system the LCD screen start flickering, here the flickering is not due to low
refresh rate but showing swapped double images and very distorted display. Even this flickering is very less
in the initial screen(angstrom boot screen) but more in the later X11 desktop screen.

Then we started decreasing pixel clock and the flickering also decreased. At 16.4 Mhz of pixel clock this type of
flickering stopped but scanning flickering started due to low pixel clock resulting low refresh rate. In this case image
is stable.

Q1) Is X11 not able to fill the framebuffer properly to sync with fast pixel clock ???
Please let us know the proper way to handle this. ?

We wanted to run a GUI based QT application also having video to be executed simultaneously,
the display size of video & GUI app is 800x480.
Q2) Is this possible to run this smoothly with OMAP 3530 ???

Q3) What is use of following configuration of LCD panel

OMAP_DSS_LCD_IVS = 1<<0,
OMAP_DSS_LCD_IHS = 1<<1,
OMAP_DSS_LCD_IPC = 1<<2,
OMAP_DSS_LCD_IEO = 1<<3,
OMAP_DSS_LCD_RF = 1<<4,
OMAP_DSS_LCD_ONOFF = 1<<5,

OMAP_DSS_LCD_TFT = 1<<20,

We have configured this as

dssdev->panel.config = OMAP_DSS_LCD_TFT;

Q4) Is this proper ?

Please solve the above queries ASAP.

WAITING FOR YOUR REPLY...

Regards...


PARTH JOSHI
Sr. Embedded Design Eng,

LUMIUM
B-304, Shapath IV,
Opp. Karnavati Club,
S G Highway, Ahmedabad-380051
Main:+91 79 40205555
Fax:+91 79 40205528
Cell: +91 8980923951