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framebuffer for au1000 based board.

Subject: framebuffer for au1000 based board.
From: Maxim Moroz <>
Date: Sat, 03 Sep 2005 06:31:49 +0400
Original-recipient: rfc822;
User-agent: Mozilla Thunderbird 1.0.6-1.1am (X11/20050721)
Hello, I'm writing framebuffer (800x600@16bpp) for au1000 based board for latest linux-2.6.13 mips kernel.
video memory is located at address 0xbe00_0000.
The problem is that I cannot correctly mmap video memory to userspace.

mmap was taken from au1500 lcd framebuffer driver(code follows)

start, fbi->fix.smem_start, off are all equal to 0xbe00_0000 (video memory start)

mmaping from userspace is working ok, but writing to mmaped memory gives no result
on display.

code like memset(0xbe00_0000,0,FB_MEM_SIZE) from kernel space is working as expected.

from userspace running test on mmaped fb gives no visible results.

cat /proc/156/maps
00400000-00407000 r-xp 00000000 08:01 27785      /root/fbtest
00446000-00447000 rw-p 00006000 08:01 27785      /root/fbtest
00447000-00449000 rwxp 00447000 00:00 0          [heap]
2aaa8000-2ab93000 rw-s be000000 08:01 17858      /dev/fb0
7fb12000-7fb27000 rwxp 7fb12000 00:00 0          [stack]

Also I have problems with ioremapping:
//info->screen_base = ioremap(AU1000VLFB_BASE_PHYS, AU1000VLFB_FB_LEN); // <-doesn't work when do 'dd if=/dev/zero of=/dev/fb0 count=2048' info->screen_base = AU1000VLFB_BASE_PHYS; // <- this one clears screen when 'dd if=/dev/zero of=/dev/fb0 count=2048'

ioremap gives me 0xc000_0000 from 0xbe00_0000. I'm not sure if this correct.

Can't resolve problem myself.
Thank you in advance!
Best Regards, Maxim Moroz.

/* fb_mmap
* Map video memory in user space. We don't use the generic fb_mmap method mainly
* to allow the use of the TLB streaming flag (CCA=6)
int au1000fb_fb_mmap(struct fb_info *fbi, struct file *file, struct vm_area_struct *vma)
 unsigned int len;
 unsigned long start=0, off;

 if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT)) {
   return -EINVAL;

 start = fbi->fix.smem_start & PAGE_MASK;
 len = PAGE_ALIGN((start & ~PAGE_MASK) + fbi->fix.smem_len);

 off = vma->vm_pgoff << PAGE_SHIFT;

 if ((vma->vm_end - vma->vm_start + off) > len) {
   return -EINVAL;

 off += start;
 vma->vm_pgoff = off >> PAGE_SHIFT;

 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 pgprot_val(vma->vm_page_prot) |= (6 << 9); //CCA=6

 vma->vm_flags |= VM_IO;

 printk("%lu %lu %lu %lu %lu\n",
         vma->vm_end - vma->vm_start

 if (remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
       vma->vm_end - vma->vm_start,
       vma->vm_page_prot)) {
   return -EAGAIN;

 return 0;

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