There is no picture in lcd

SGaist

What OS are you running on your target ?

junzhang

@SGaist
/ # uname -a
uname -a
Linux mdm9607 3.18.20 #1 PREEMPT Mon Feb 13 10:40:15 CST 2017 armv7l GNU/Linux
/ #

SGaist

The distribution would be more useful.

Also, are you running your application as root ?

What exact message are you getting on the console when you launch the application ?

junzhang

@SGaist
yes, we run an application with root access.
we test with Qt/examples/qws/framebuffer, the message is below:

root@mdm9607:/home# ./framebuffer
./framebuffer
The framebuffer device was opened successfully.

Fixed screen info:
id: mdssfb_20000
smem_start: 0x8fc80000
smem_len: 155648
type: 0
type_aux: 0
visual: 2
xpanstep: 1
ypanstep: 1
ywrapstep: 0
line_length: 480
mmio_start: 0x0
mmio_len: 0
accel: 0

The framebuffer device was mapped to memory successfully.

Successfully switched to graphics mode.

Variable screen info:
xres: 240
yres: 320
xres_virtual: 240
yres_virtual: 320
yoffset: 0
xoffset: 0
bits_per_pixel: 16
grayscale: 0
red: offset: 11, length: 5, msb_right: 0
green: offset: 5, length: 6, msb_right: 0
blue: offset: 0, length: 5, msb_right: 0
transp: offset: 0, length: 0, msb_right: 0
nonstd: 0
activate: 16
height: -1
width: -1
accel_flags: 0x0
pixclock: 0
left_margin: 0
right_margin: 0
upper_margin: 0
lower_margin: 0
hsync_len: 0
vsync_len: 0
sync: 0
vmode: 0

Frame Buffer Performance test...
Average: 395 usecs
Bandwidth: 375.791 MByte/Sec
Max. FPS: 2531.646 fps

Will draw 3 rectangles on the screen,
they should be colored red, green and blue (in that order).
Done.
root@mdm9607:/home#

l change the Qt/examples/qws/framebuffer/main.c
void drawRect_rgb16(int x0, int y0, int width, int height, int color)
{
const int bytesPerPixel = 2;
const int stride = finfo.line_length / bytesPerPixel;
const int red = (color & 0xff0000) >> (16 + 3);
const int green = (color & 0xff00) >> (8 + 2);
const int blue = (color & 0xff) >> 3;
const short color16 = blue | (green << 5) | (red << (5 + 6));

short *dest = (short*)(frameBuffer)
	  + (y0 + vinfo.yoffset) * stride
	  + (x0 + vinfo.xoffset);

int x, y;
for (y = 0; y < height; ++y) {
    for (x = 0; x < width; ++x) {
        dest[x] = color16;
    }
    dest += stride;
}//add by junzhang
if(ioctl(fbFd, FBIOPAN_DISPLAY, &vinfo)!= 0)
{
    return -1;
}//

}
there is nothing in lcd unless l add that code when l test with framebuffer example, the message is the same whether l add that code or not.

junzhang

@SGaist
l want to add
if(ioctl(fbFd, FBIOPAN_DISPLAY, &vinfo)!= 0)
{
return -1;
}/
to the code which update framebuffer in Qt,
it's mean that if something update in Qt, it will be write data to framebuffer, so, i will add that code in the function which update framebuffer.
it's that ok?
if ok, pls tell which function update framebuffer. thx.

SGaist

You likely should check the QLinuxFbScreen class.

junzhang

@SGaist
thx, l found it and it's show ok.

SGaist

Do you mean by adding you ioctl code ?

junzhang

@SGaist
yes, l add inctl to refresh data to lcd.

SGaist

Ok

Then please mark the thread as solved using the "Topic Tools" button so that other forum users may know a solution has been found :)