From: Jussi Kivilinna <jussi.kivilinna@iki•fi>
To: Oliver Neukum <oliver@neukum•org>
Cc: Ming Lei <tom.leiming@gmail•com>,
linux-usb@vger•kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
Network Development <netdev@vger•kernel.org>
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 [thread overview]
Message-ID: <51BD94F5.2060803@iki.fi> (raw)
In-Reply-To: <6777683.xBFsv58ruI@linux-5eaq.site>
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
>
>
next prev parent reply other threads:[~2013-06-16 10:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130614133803.25747.98705.stgit@localhost6.localdomain6>
[not found] ` <20130614133803.25747.98705.stgit-bi+AKbBUZKagILUCTcTcHdKyNwTtLsGr@public.gmane.org>
2013-06-15 7:41 ` [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped Ming Lei
2013-06-15 10:19 ` Jussi Kivilinna
[not found] ` <51BC3F9E.3010605-X3B1VOXEql0@public.gmane.org>
2013-06-15 12:07 ` Ming Lei
[not found] ` <CACVXFVMe9fgdiDTRC0rWvwZJM8aT7AZY8Q1MwiOTc4ks0PQPOg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-06-15 13:10 ` Jussi Kivilinna
2013-06-15 13:22 ` Jussi Kivilinna
[not found] ` <51BC6A96.7030707-X3B1VOXEql0@public.gmane.org>
2013-06-16 8:21 ` Oliver Neukum
2013-06-16 10:35 ` Jussi Kivilinna [this message]
2013-06-28 12:39 ` Jussi Kivilinna
2013-06-28 12:58 ` Oliver Neukum
2013-06-15 13:47 ` Ming Lei
2013-06-16 10:34 ` Jussi Kivilinna
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