QVGA for Neo
john cass
johnpcass at yahoo.com
Fri Sep 28 11:52:00 CEST 2007
Hello
Update on the wierd 'one line only' effect I see when changing framebuffer with
fbset:
> 3) There is a problem when setting the pixclock using fbset in that it causes
> the console to freeze - it looks like only the top line of the console is
> working and when running mplayer from this console, only the top line (y=0)
> is shown. If I run the fbset -pixclock command while X is displaying then
> kill X (console takes over) it works fine. I am trying to track this
> problem - its somewhere in fbcon.c to do with a call to fbcon_modechanged()
> I think...
I have found the source of this problem: the s3c2410fb.c LCD controller driver
in function fb_set_par (which is called when fbset changes the framebuffer
characteristics) does this:
fbi->fb->fix.line_length = (var->width*var->bits_per_pixel)/8;
var->width is supposed to hold the width in mm of the screen (according to fb.h),
not the X pixel resolution. fbset always sets var->width to 0.
fb->fix.line_length is used to calculate offsets to the 'next line' when writing to
the framebuffer so the effect of a 0 here is that you only ever get one line (y=0)
it should be set to the number of bytes in a line in the framebuffer
this line should probably be changed to :
fbi->fb->fix.line_length = (var->xres_virtual*var->bits_per_pixel)/8;
Regards
John
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