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Date: Fri, 10 Mar 2017 10:31:13 +0000
From: Brian Starkey <brian.starkey@arm.com>
Subject: Re: [RFC PATCH 00/12] Ion cleanup in preparation for moving out of
 staging
Message-ID: <20170310103112.GA15945@e106950-lin.cambridge.arm.com>
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To: Laura Abbott <labbott@redhat.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>, Mark Brown <broonie@kernel.org>, Michal Hocko <mhocko@kernel.org>, Sumit Semwal <sumit.semwal@linaro.org>, Riley Andrews <riandrews@android.com>, Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>, Rom Lemarchand <romlem@google.com>, devel@driverdev.osuosl.org, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, "linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-arm-kernel@lists.infradead.org, "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, Daniel Vetter <daniel.vetter@intel.com>, linux-mm@kvack.org

Hi,

On Thu, Mar 09, 2017 at 09:38:49AM -0800, Laura Abbott wrote:
>On 03/09/2017 02:00 AM, Benjamin Gaignard wrote:

[snip]

>>
>> For me those patches are going in the right direction.
>>
>> I still have few questions:
>> - since alignment management has been remove from ion-core, should it
>> be also removed from ioctl structure ?
>
>Yes, I think I'm going to go with the suggestion to fixup the ABI
>so we don't need the compat layer and as part of that I'm also
>dropping the align argument.
>

Is the only motivation for removing the alignment parameter that
no-one got around to using it for something useful yet?
The original comment was true - different devices do have different
alignment requirements.

Better alignment can help SMMUs use larger blocks when mapping,
reducing TLB pressure and the chance of a page table walk causing
display underruns.

-Brian

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