linux-kernel - Re: [PATCH v6 03/14] videobuf2: handle V4L2 buffer cache flags

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Message-ID: <9c6a347e-1cbf-3486-896a-124375fd225c@xs4all.nl>
Date:   Tue, 2 Jun 2020 14:21:20 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Hans Verkuil <hans.verkuil@...co.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tomasz Figa <tfiga@...omium.org>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH v6 03/14] videobuf2: handle V4L2 buffer cache flags

On 02/06/2020 14:10, Sergey Senozhatsky wrote:
> On (20/06/02 12:27), Hans Verkuil wrote:
> [..]
>>> Sorry, Hans, do you suggest to have something like this:
>>>
>>> 	if (q->memory == VB2_MEMORY_DMABUF) {
>>> 		vb->need_cache_sync_on_finish = 0;
>>> 		vb->need_cache_sync_on_prepare = 0;
>>> 		b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
>>> 		b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
>>> 		return;
>>> 	}
>>>
>>> I didn't clear the ->flags there because we clear the vb flush/sync
>>> flags: ->need_cache_sync_on_finish/prepare are zeros for DMABUF memory
>>> type. Which is equivalent to passing V4L2_BUF_FLAG_NO_CACHE_INVALIDATE
>>> V4L2_BUF_FLAG_NO_CACHE_CLEAN. IOW we would clearing both "vb's do cache
>>> sync" and request's "do not cache sync".
>>
>> Ah, yes. In that case the v4l-utils patch is likely wrong.
>> Can you take a look at that patch?
> 
> Hans, are we talking about "v4l2-utils: test cache_hints for MMAP queues"
> patch? I can take a look, yes.

Yes, that's the one.

	Hans