drm_vm.c: many arches equate remap_pfn_range() and io_remap_pfn_range()

[Sascha Hauer]

On Wed, Aug 29, 2012 at 06:29:53PM -0400, Robert P. J. Day wrote:
> 
>   a pedantic observation, you can do with it what you wish (i'm not a
> list subscriber).  in drivers/gpu/drm/drm_vm.c, we read (line 629):
> 
> #if !defined(__arm__)
>                 if (io_remap_pfn_range(vma, vma->vm_start,
>                                        (map->offset + offset) >> PAGE_SHIFT,
>                                        vma->vm_end - vma->vm_start,
>                                        vma->vm_page_prot))
>                         return -EAGAIN;
> #else
>                 if (remap_pfn_range(vma, vma->vm_start,
>                                         (map->offset + offset) >> PAGE_SHIFT,
>                                         vma->vm_end - vma->vm_start,
>                                         vma->vm_page_prot))
>                         return -EAGAIN;
> #endif

This code goes down to:

commit 4b7fb9b5746554d460e7bc986341d4b2db01e0b6
Author: Jordan Crouse <jcrouse at codeaurora.org>
Date:   Thu May 27 13:40:26 2010 -0600

    drm: Add __arm defines to DRM
    
    Add __arm defines to specify behavior specific for
    an ARM processor.
    
    Signed-off-by: Jordan Crouse <jcrouse at codeaurora.org>
    Signed-off-by: Dave Airlie <airlied at redhat.com>

Even at that time io_remap_pfn_range on arm was defined as:

> 
> #define io_remap_pfn_range(vma,from,pfn,size,prot) \
>                 remap_pfn_range(vma, from, pfn, size, prot)
> 
> so it's not clear what the preprocessor test is for.  admittedly, it
> should work, it just seems unnecessary.  and it makes the code more
> confusing than it needs to be, but perhaps i've just misread
> something.

I agree that this shouldn't be necessary.

Sascha


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