From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Subject: Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA
 aligned and are about to be DMA mapped
Date: Sun, 16 Jun 2013 13:35:33 +0300
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Cc: Ming Lei <tom.leiming@gmail.com>, linux-usb@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Network Development <netdev@vger.kernel.org>
To: Oliver Neukum <oliver@neukum.org>
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On 16.06.2013 11:21, Oliver Neukum wrote:
> On Saturday 15 June 2013 16:22:30 Jussi Kivilinna wrote:
> 
>> Hm.. rethink this a bit.
>>
>> Transfer buffer might be dma aligned but shorter than cacheline and end of cacheline
>> used as something else. Manual alignment by host driver does not catch that
>> or fix that.
>> So, yes.. dma mapping should work with unaligned buffers, but maybe the actual
>> problem is multiple buffers from same cacheline.
> 
> The buffers kmalloc() returns are OK in that regard. A driver that uses
> a buffer for anything but buffering is buggy.

Ok, I'll look at that direction. Thanks.

-Jussi

> 
> 	Regards
> 		Oliver
> 
>