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Date: Thu, 9 Jun 2016 09:25:02 +0100
From: Brian Starkey <brian.starkey@arm.com>
To: Laura Abbott <labbott@redhat.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>,
        John Stultz <john.stultz@linaro.org>,
        Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>,
        Riley Andrews <riandrews@android.com>,
        Laura Abbott <labbott@fedoraproject.org>,
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        Bryan Huntsman <bryanh@codeaurora.org>,
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Subject: Re: [RFC][PATCH 6/6] staging: android: ion: Introduce new ioctls for
 dynamic heaps
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Hi Laura,

On Wed, Jun 08, 2016 at 12:14:12PM -0700, Laura Abbott wrote:
>
>For now I'm just going to focus on comments not about the heap ID mapping
>because I'm leaning towards dropping the heap ID mapping.
>

Fair enough. Like you said, giving userspace enough information to just
figure out the right heap IDs is already a big improvement.

>
>I'm not that familiar with the DRM ioctls but this sounds like a
>good suggestion. One less ioctl to worry about.
>

Sorry, I probably should have pointed to an example:
http://lxr.free-electrons.com/source/drivers/gpu/drm/drm_crtc.c#L2325

>>>+ */
>>>+struct ion_heap_query {
>>>+    __u32 cnt; /* Total number of heaps to be copied */
>>>+    __u64 heaps; /* buffer to be populated */
>>
>>I guess this field needs explicit alignment to 64 bits
>>
>
>Yes, I was going by the suggestion in botching-up-ioctls.txt
>
>https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt#n42
>

The type is fine, but you should add a 32-bit padding field before
heaps:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt#n32

Cheers,

-Brian