On Mon, Apr 22, 2013 at 12:39:23PM +0530, Girish K S wrote:
> From: Girish K S <girishks2000@gmail.com>
> 
> The 64xx spi driver supports partial polling mode.
> Only the last chunk of the transfer length is transferred
> or recieved in polling mode.

This appears to have a very noticable negative impact on SPI performance
on my S3C6410 based system.  Not delved into it to test why but are you
sure it's not mistakenly selecting polling?