Re: [Linux-fbdev-devel] 3DFX mmio code to test with

[Antonino D. <ad...@po...>]

On Fri, 2002-05-03 at 08:03, Ani Joshi wrote:
> 
> Well, I didn't try running this code, but its looks from your code below
> that your mmap() is wrong.  The first argument in mmap is rarely used and
> typically a hint.  You should be using the mmio address (fb_fix.mmio_start)
> in the last argument instead of the first, and have the first agrument 0.
> The last argument is the offset (in this case the physical offset in
> memory).
> 
> After further looking at your code, it seems you are mmaping /dev/fb for
> your MMIO.  Is this even possible?  Shouldn't you be mapping /dev/mem?
> Has someone changed the fbdev layer so you can mmap mmio via /dev/fb?
> 
> 
DirectFB mmaps mmio via /dev/fb.  For the first argument (length), you
have to use a value <= fix.mmio_len, and for the last argument (offset),
you have to use a value >= fix.smem_len.  At (offset == fix.smem_len),
the actual mmio offset mmaped is at 0.  

By the way, may have to generally use NULL for the first argument
(start).

Tony

> ani
> 
> 
> On Thu, 2 May 2002, James Simmons wrote:
> 
> > 	dst2 = mmap(fb_fix.mmio_start, fb_fix.mmio_len, PROT_WRITE,MAP_SHARED, fbd, 0);
> > 	if (!dst2) {
> > 		fprintf(stderr, "MMap of MMIO of /dev/fb%d failed\n", fbnum);
> > 		exit(1);
> > 	}
> 
> 
> 
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