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$0, height20 which result in
stable picture, but
the following timing gave me stable ppicture with LCD:
Pixel clocke00
Width$0
HeightQ2 <<------------- instead of 320 !!
Hfp=1
Hbp0
HSW
Vfp=1
Vbp=1
VSW
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
On Sat, Dec 5, 2015 at 8:03 AM, Ran Shalit [off-list ref] 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$0, height20 which result in
stable picture, but
the following timing gave me stable ppicture with LCD:
Pixel clocke00
Width$0
HeightQ2 <<------------- instead of 320 !!
Hfp=1
Hbp0
HSW
Vfp=1
Vbp=1
VSW
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