I confirm there is no chance to use framebuffer mmap() and MAP_SHARED to
access framebuffer screen memory with _coldfire_ _mcf5307_.
Actually, i call
buffer = mmap(0, buflen, PROT_WRITE, MAP_SHARED, fd, 0);
over fd open on "/dev/fb0" as ORDWR.
Call fail inside
mm/nommu.c, validate_mmap_request(), line 920
if (flags & MAP_SHARED) {
/* do checks for writing, appending and locking */
if ((prot & PROT_WRITE) &&
!(file->f_mode & FMODE_WRITE))
return -EACCES;
if (IS_APPEND(file->f_path.dentry->d_inode) &&
(file->f_mode & FMODE_WRITE))
return -EACCES;
if
(locks_verify_locked(file->f_path.dentry->d_inode))
return -EAGAIN;
if (!(capabilities & BDI_CAP_MAP_DIRECT))
{
--> printk (KERN_INFO "ENODEV 2\n");
--> return -ENODEV;
}
So, as i explained, i cannot have BDI_CAP_MAP_DIRECT for this
architecture, and the mmap call using MAP_SHARED fails.
Looking the code, error is still at a mmap params "validation" level,
and far from any "fb_mmap" to get called.
Code is complex, and still i can miss something. Anyway i hope you can
confirm i cannot use mmap() to access framebuffer for this cpu, or
maybe, you can suggest me some example that can do it.
Regards,
Angelo
On 12/12/2012 23:21, Gavin Lambert wrote:
> Quoth angelo:
>> thanks, well, i implemented the handler:
>>
>> static int amcorefb_mmap(struct fb_info *info, struct vm_area_struct
>> *vma) {
>
> No, that's not the right one. You don't need to implement that.
>
>> Seems i miss the "get_unmapped_area/BDI_CAP_MAP_DIRECT) capability.
>
> fbmem.c implements the main get_unmapped_area handler. In your framebuffer
> driver you just need to either implement fb_get_unmapped_area or (easier,
> but only works on nommu) set fix.smem_start and .smem_len correctly in your
> fb_info.
>
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