There is no picture in lcd

[junzhang]

Hi,
l cross compiling qt for armv7, and then write an example to test, the code below

int main(int argc, char *argv[])
{
 QApplication a(argc, argv);
    MainWindow w;
    w.setStyleSheet("background-color:blue;");
    w.show();
}
but there is no picture in lcd, l change the code below
int main(int argc, char *argv[])
{
	int fbFd = 0;
	const char *devfile = "/dev/fb0";
	fbFd = open(devfile, O_RDWR);
	if (ioctl(fbFd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
		perror("Error reading variable information");
		exit(3);
    }
    if (fbFd == -1) {
		perror("Error: cannot open framebuffer device");
		exit(1);
    }
	if(ioctl(fbFd, FBIOPAN_DISPLAY, &vinfo)!= 0)
    {
        return -1;
    }
	if(ioctl(fbFd, FBIOPAN_DISPLAY, &vinfo)!= 0)
    {
        return -1;
    }
	
    QApplication a(argc, argv);
    MainWindow w;

    w.setStyleSheet("background-color:blue;");
    w.show();
	if (ioctl(fbFd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
		perror("Error reading variable information");
		exit(3);
    }
	if (ioctl(fbFd, FBIOGET_FSCREENINFO, &finfo) == -1) {
		perror("Error reading fixed information");
		exit(2);
    }
	if(ioctl(fbFd, FBIOPAN_DISPLAY, &vinfo)!= 0)
    {
        return -1;
    }
    return a.exec();
}

after compile and then download, the lcd can show picture,
so, why we must add this code? whether there is wrong for my cross compiling?

Edit: p3c0

[SGaist]

Hi and welcome to devnet,

There's not enough details:

• What version of Qt are you using ?
• What backend do you want to use for your application
• What error message did you got ?
• What hardware are you targeting ?
• What distribution is it running ?
• How are you starting your application on the device ?

[Devopia53]

@junzhang

Hi.

What is the platform plugin are you setting?
If it is not setting, the QT_QPA_PLATFORM environment variable parameter can be used to setting or the -platform command-line can be used with the same syntax.

Like this(for example):
QT_QPA_PLATFORM=linuxfb:fb=/dev/fb0
or
./yourapp -platform linuxfb:fb=/dev/fb0

[junzhang]

Dear Devopia53,
how can l set my platform plugin?
my profile is below:

export TSLIB_ROOT=/usr/local/tslib
export TSLIB_TSDEVICE=/dev/event0
export TSLIB_FBDEVICE=/dev/fb0
export TSLIB_PLUGINDIR=/usr/local/tslib/lib/ts
export TSLIB_CONSOLEDEVICE=none
export TSLIB_CONFFILE=/usr/local/tslib/etc/ts.conf
export POINTERCAL_FILE=/etc/pointercal
export TSLIB_CALIBFILE=/etc/pointercal
#export QWS_SIZE=128x128
export QWS_MOUSE_PROTO=Tslib:/dev/event0
export QTDIR=/usr/local/qt
export QPEDIR=/usr/local/qt
export QWS_DISPLAY=LinuxFb:/dev/fb0
export LD_LIBRARY_PATH=$TSLIB_ROOT/lib:$QTDIR/lib:$LD_LIBRARY_PATH
export QT_QWS_FONTDIR=$QTDIR/lib/fonts
export LD_LIBRARY_PATH=/usr/local/qtlib/lib:$LD_LIBRARY_PATH
export PATH PS1 OPIEDIR QPEDIR QTDIR EDITOR TERM

[SGaist]

Using Qt 4?

[junzhang]

@SGaist
yes, qt4.8.5

[SGaist]

Did you check the permissions on the frame buffer device ?

On a side note, if locked on Qt 4, the you should go with 4.8.7 which is the latest and last version of the Qt 4 series. Otherwise, you should go with Qt 5.

[junzhang]

@SGaist
here is my cross compile config:
sudo ./configure --prefix=/usr/local/qt4.8.5-arm -opensource -release -shared -Declarative -importdir /opt/imports -fast -no-largefile -qt-sql-sqlite -qt3support -exceptions -xmlpatterns -no-glib -no-phonon -no-mmx -no-3dnow -no-sse -no-sse2 -svg -no-webkit -qt-zlib -qt-libtiff -qt-libpng -qt-libjpeg -make libs -make tools -nomake examples -nomake docs -nomake demo -no-nis -no-cups -iconv -no-dbus -xplatform qws/linux-arm-g++ -embedded arm -little-endian -qt-freetype -depths 16,24,32 -qt-gfx-linuxfb -qt-gfx-transformed -qt-gfx-multiscreen -no-gfx-vnc -no-gfx-qvfb -qt-kbd-linuxinput -no-kbd-qvfb -armfpa -no-mouse-qvfb -qt-mouse-linuxtp -qt-mouse-tslib -DQT_QLOCALE_USES_FCVT -DQT_NO_QWS_CURSOR -no-pch -I/usr/local/tslib/include -L/usr/local/tslib/lib -confirm-license

[SGaist]

That doesn't answer my question about the permissions of /dev/fb0 on your target.

On a side note, never develop nor build as root. If something goes wrong there's no restriction at what can be destroyed on your system.

[junzhang]

@SGaist
/ # ls /dev/fb0 -l
crw-rw---- 1 root root 29, 0 Jan 1 00:00 /dev/fb0

when l use Qt/qt/qt-everywhere-opensource-src-4.8.5/examples/qws/framebuffer to test, it's ok,
your mean it's maybe to compile use "sudo"?
l will re-compile it with no "sudo".

[SGaist]

How are you calling your application on the command line ?

[junzhang]

@SGaist
./test_demo -qws

[junzhang]

@SGaist
l use normal user to cross compile qt5.7.0, it's still unshow anything unless l add "ioctl(fbFd, FBIOGET_FSCREENINFO, &finfo)".and it just to show one frame,
my cross compile steps is below:

1. download tslib1.4.tar.gz$ ./autogen.sh
   $ tar zxvf tslib1.4.tar.gz
   $ ./configure CC=arm-none-linux-gnueabihf-gcc CXX=arm-none-linux-gnueabihf-g++ --prefix=/usr/local/tslib --host=arm-none-linux-gnueabihf ac_cv_func_malloc_0_nonnull=yes
   $make
   $sudo make install

2. download qt-everywhere-opensource-src-5.7.0.tar.gz
   2.1: tar zxvf qt-everywhere-opensource-src-5.7.0.tar.gz
   2.2: vim qt-everywhere-opensource-src-5.7.0/qtbase/mkspecs/linux-arm-gnueabi-g++/qmake.conf

    include(../common/linux.conf)
   + QT_QPA_DEFAULT_PLATFORM = linux #eglfs 
   +QMAKE_CFLAGS_RELEASE += -O2 -march=armv7-a
   + QMAKE_CXXFLAGS_RELEASE += -O2 -march=armv7-a
   

   arm-linux-geneabi-xxx change to arm-none-linux-geneabi-xxx
   2.3: vim build.sh

   #!/bin/sh
   ./configure
   -v
   -prefix /opt/qt5.7.0
   -release
   -opensource
   -make libs
   -xplatform linux-arm-gnueabi-g++
   -optimized-qmake
   -pch
   -qt-sql-sqlite
   -qt-libjpeg
   -qt-zlib
   -no-opengl
   -skip qt3d
   -skip qtcanvas3d
   -skip qtpurchasing
   -no-sse2
   -no-openssl
   -no-nis
   -no-cups
   -no-glib
   -no-iconv
   -nomake examples
   -nomake tools
   -skip qtvirtualkeyboard
   -I/usr/local/tslib/include
   -L/usr/local/tslib/lib

   exit
   2.4: ./build.sh
   2.5: make
   2.6: sudo make install

3. tar /usr/local/tslib and /opt/qt5.7.0

4. for arm platform
   4.1: cp qt5.7.0.tar.gz and tslib.tar.gz to /opt
   4.2: tar zxvf qt5.7.0.tar.gz and tar zxvf tslib.tar.gz
   4.3: vim /etc/profile
   #add for qt
   export TSLIB_ROOT=/opt/tslib
   export QT_ROOT=/opt/qt5.7.0
   export TSLIB_TSDEVICE=/dev/input/event0
   export TSLIB_TSEVENTTYPE=input
   export TSLIB_CONFFILE=/opt/tslib/etc/ts.conf
   export TSLIB_CALIBFILE=/etc/pointercal
   export TSLIB_PLUGINDIR=/opt/tslib/lib/ts
   export TSLIB_CONSOLEDEVICE=none
   export TSLIB_FBDEVICE=/dev/fb0
   export QWS_MOUSE_PROTO=tslib:/dev/input/event0
   export LD_LIBRARY_PATH=/lib:/usr/lib:$QT_ROOT/lib:$TSLIB_ROOT/lib:$TSLIB_ROOT/lib/
   export QT_QPA_PLATFORM_PLUGIN_PATH=$QT_ROOT/plugins
   export QT_QPA_PLATFORM=linuxfb:tty=/dev/fb0
   export QT_QPA_FONTDIR=$QT_ROOT/lib/fonts
   export QT_QPA_GENERIC_PLUGINS=tslib
   4.4: source /etc/profile
   4.5: cd /opt/tslib/bin and then run ./ts_calibrate
   4.6: write an test example
   qmake test_qt.pro
   make
   adb push test_qt /home/demo
   4.6: cd /home/demo and then ./test_qt

after l run ./test_qt, there is nothing in lcd,so l write test framebuffer code to test fb driver, it's show ok,
but if l add "ioctl(fbFd, FBIOPAN_DISPLAY, &vinfo)" in test_qt demo, it's show ok, but it just show one frame, unable to self-refresh,

for step 4.5 and 4.6, l use another method to test, but there is still nothing in lcd.
4.5: ./ts_calibrate -qws
4.6: ./test_qt -qws

note: there is no touch screen in my whole steps.

[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.