svn commit: r260440 - head/sys/arm/conf

[Nathan Whitehorn]

On 01/07/14 22:40, Ian Lepore wrote:
> Author: ian
> Date: Wed Jan  8 03:40:18 2014
> New Revision: 260440
> URL: http://svnweb.freebsd.org/changeset/base/260440
>
> Log:
>   Add option USB_HOST_ALIGN to configs that contain 'device usb'.  Setting
>   this to the cache line size is required to avoid data corruption on armv4
>   and armv5, and improves performance on armv6, in both cases by avoiding
>   partial cacheline flushes for USB IO.
>   
>   All these configs already exist in 10-stable.  A few that don't (and
>   thus can't be MFC'd yet) will be committed separately.
>

There has to be -- and I do not mean this as a criticism of your patch
-- a better solution to this problem than USB_HOST_ALIGN. Isn't busdma
supposed to handle this kind of thing? Why is USB different?
-Nathan