linux-kernel - Re: [PATCH] media: vb2: always set buffer cache sync hints

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Date:   Fri, 27 Nov 2020 18:44:26 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Tomasz Figa <tfiga@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH] media: vb2: always set buffer cache sync hints

On (20/11/27 18:41), Sergey Senozhatsky wrote:
> We need to always set ->need_cache_sync_on_prepare and
> ->need_cache_sync_on_finish when we initialize vb2 buffer.
> 
> Currently these flags are set/adjusted only in V4L2's
> vb2_queue_or_prepare_buf(), which means that for the code
> paths that don't use V4L2 vb2 will always tell videobuf2
> core to skip ->prepare() and ->finish() cache syncs/flushes.
> 
> This is a quick solution that should do the trick. The
> proper fix, however, is much more complicated and requires
> a rather big videobuf2 refactoring - we need to move cache
> sync/flush decision making out of core videobuf2 to the
> allocators.
> 
> Reported-by: Tomasz Figa <tfiga@...omium.org>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>

Fixes: f5f5fa73fbfb ("media: videobuf2: handle V4L2 buffer cache flags")

	-ss