Hi,
I am using Lepton Floppy Linux and Redhat Linux. When I am trying to execute
the Framebuffer sample program, It is displaying the below error message:
The framebuffer device was opened successfully.
Error reading fixed screen information.
Error reading variable screen information.
Actually, It is opening Framebuffer (/dev/fb0) device successfully. But, it is
unable to read the Fixed screen information (FBIOGET_FSCREENINFO) and Variable
screen information (FBIOGET_VSCREENINFO). fbset command is also not working.
What can I do? Please give me the solution. Here, I am giving the sample code
of framebuffer. Please run this and see the output.
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main(void)
{
int fbfd = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screensize = 0;
char *fbp = 0;
/* Open the file for reading and writing */
fbfd = open("/dev/fb0", O_RDWR);
if (!fbfd)
{
printf("Error: cannot open framebuffer device.\n");
exit(1);
}
printf("The framebuffer device was opened successfully.\n");
/* Get fixed screen information */
if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo))
{
printf("Error reading fixed screen information.\n");
exit(2);
}
else
printf("\nSuccesfully Read the Fixed Screen Information\n");
/* Get variable screen information */
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo))
{
printf("Error reading variable screen information.\n");
exit(3);
}
else
printf("\n Successfully Read the Variable Information\n");
printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel );
/* Figure out the size of the screen in bytes */
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
/* Map the device to memory */
fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
fbfd, 0);
if ((int)fbp == -1)
{
printf("Error: failed to map framebuffer device to memory.\n");
exit(4);
}
printf("The framebuffer device was mapped to memory successfully.\n");
munmap(fbp, screensize);
close(fbfd);
return 0;
}
I will be waiting for your reply. Thank you.
With regards,
Chandra.
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