From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] USB: set device dma_mask without reference to global data
Date: Wed, 8 May 2013 16:07:54 +0200 [thread overview]
Message-ID: <201305081607.54839.arnd@arndb.de> (raw)
In-Reply-To: <518A582C.8070600@gmail.com>
On Wednesday 08 May 2013, Rob Herring wrote:
> On 05/08/2013 02:11 AM, Matthijs Kooijman wrote:
> > https://lkml.org/lkml/2012/12/4/54
> >
> > And here's the previous attempt, to which Rob Herring refers in a reply.
> >
> > https://lists.ozlabs.org/pipermail/devicetree-discuss/2012-March/013180.html
>
> I believe most of the issues have been around supporting ARM LPAE
> systems. There is a much more simple approach to address this by using
> the dma_addr_t size to set the coherent_dma_mask which I have queued for
> 3.11:
>
> https://patchwork-mail1.kernel.org/patch/2495861/
Hmm, this approach seems wrong -- a lot of devices I expect cannot
actually do DMA to addresses beyond 4GB. A better default would
be to use a 32 bit mask for all devices and override the ones that
actually matter for performance and are known to be 64-bit DMA
capable.
Laura, you obviously tried this code on an LPAE-enabled system. Have
you had a look in the hardware manual which DMA masters in the
system are actually 64-bit capable?
Arnd
next prev parent reply other threads:[~2013-05-08 14:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-07 22:53 [PATCH] USB: set device dma_mask without reference to global data Stephen Warren
2013-05-07 23:04 ` Greg Kroah-Hartman
2013-05-07 23:42 ` Arnd Bergmann
2013-05-08 14:14 ` Alan Stern
2013-05-08 15:10 ` Arnd Bergmann
2013-05-09 21:33 ` Russell King - ARM Linux
2013-05-08 1:13 ` Peter Chen
2013-05-08 2:26 ` Stephen Warren
2013-05-08 2:54 ` Peter Chen
2013-05-08 7:11 ` Matthijs Kooijman
2013-05-08 7:28 ` Matthijs Kooijman
2013-05-08 13:50 ` Rob Herring
2013-05-08 14:07 ` Arnd Bergmann [this message]
2013-05-08 7:24 ` Arnd Bergmann
2013-05-09 21:39 ` Russell King - ARM Linux
2013-05-08 22:42 ` Stephen Warren
2013-05-09 21:36 ` Russell King - ARM Linux
2013-05-08 5:11 ` Tony Prisk
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201305081607.54839.arnd@arndb.de \
--to=arnd@arndb$(echo .)de \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox