On Sat, Dec 5, 2015 at 8:03 AM, Ran Shalit <ranshalit@gmail.com> wrote:
Hello,
I would like to ask what is the effect of wiping frame buffer (dd if=/dev/zero of=/dev/fb0) ? I have some issue with framebuffer timing on LCD 240x320. I could not find a timing with width=240, height=320 which result in stable picture, but the following timing gave me stable ppicture with LCD:
Pixel clock=6500
Width=240 Height=512 <<------------- instead of 320 !! Hfp=1 Hbp=100 HSW=14 Vfp=1 Vbp=1 VSW=10
The only strange thing is that I had to use height 512 instead of 320. When I try to render image it is stable but it starts in different line every time. And here comes the important part: After doing:
dd if=/dev/zero of=/dev/fb0
It resolved the issue , and a new image starts from line 0.
I don't understand why. Does anyone have any idea ? Do you think I still have a timing problem with LCD ?
Regards, Ran
Hi, I wanted to add that framebuffer is configured as following: fbset -fb /dev/fb0 -xres 240 -yres 320 -vxres 240 -vyres 320 so, I don't know why dd if=/dev/zero of=/dev/fb0 results in image correct display starting with line 0 on the screen. I think that writing the image to framebuffer should have filled the complete buffer. Regards, Ran