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Subject: Re: [PATCHv4 01/11] videobuf2: add cache management members
To:     Sergey Senozhatsky <senozhatsky@chromium.org>
Cc:     Hans Verkuil <hans.verkuil@cisco.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Sakari Ailus <sakari.ailus@iki.fi>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Pawel Osciak <posciak@chromium.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
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 <20200307112838.GA125961@google.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
Message-ID: <a4d85ac3-0eea-bc19-cd44-0c8f5b71f6bc@xs4all.nl>
Date:   Sat, 7 Mar 2020 12:47:00 +0100
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On 07/03/2020 12:28, Sergey Senozhatsky wrote:
> On (20/03/07 11:10), Hans Verkuil wrote:
> [..]
>>>>> @@ -564,6 +573,7 @@ struct vb2_queue {
>>>>>  	unsigned			requires_requests:1;
>>>>>  	unsigned			uses_qbuf:1;
>>>>>  	unsigned			uses_requests:1;
>>>>> +	unsigned			allow_cache_hints:1;
>>>
>>> Shall I use "unsigned int" here instead of "unsigned"?
>>
>> The vb2_queue bitfields are the only places in that header were 'unsigned' is
>> used. I think that that should be fixed in a separate patch. It's nice to have
>> it consistent.
>>
>> Put that patch in the beginning of the series, that way I can pick it up in the
>> next pull request.
> 
> OK, done.
> 
> For the time being the series has moved to github public repo [0],
> I'll try to run more 'twisty' cases and re-submit once it survives
> beating.

Create those tests in v4l2-compliance: that's where they belong.

You need these tests:

For non-MMAP modes:

1) test that V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS is never set.

If V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS is not set, then:

1) attempting to use V4L2_FLAG_MEMORY_NON_CONSISTENT will clear the flag
   upon return (test with both reqbufs and create_bufs).
2) attempting to use V4L2_BUF_FLAG_NO_CACHE_INVALIDATE or V4L2_BUF_FLAG_NO_CACHE_CLEAN
   will clear those flags upon return (do we actually do that in the patch series?).

If V4L2_BUF_CAP_SUPPORTS_CACHE_HINTS is set, then:

1) set V4L2_FLAG_MEMORY_NON_CONSISTENT in reqbufs, but clear in create_bufs:
   this should fail.
2) clear V4L2_FLAG_MEMORY_NON_CONSISTENT in reqbufs, but set in create_bufs:
   this should fail.
3) set V4L2_FLAG_MEMORY_NON_CONSISTENT in both reqbufs and create_bufs: this should
   work.
4) clear V4L2_FLAG_MEMORY_NON_CONSISTENT in both reqbufs and create_bufs: this should
   work.
5) you can use V4L2_BUF_FLAG_NO_CACHE_INVALIDATE or V4L2_BUF_FLAG_NO_CACHE_CLEAN
   without these flags being cleared in v4l2_buffer.

All these tests can be done in testReqBufs().

Regards,

	Hans

> 
> [0] https://github.com/sergey-senozhatsky/v4l2-mmap-cache-flags
> 
> 	-ss
>