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Date:   Wed, 22 Jan 2020 15:37:14 +0900
From:   Sergey Senozhatsky <senozhatsky@chromium.org>
To:     Hans Verkuil <hverkuil@xs4all.nl>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        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
Subject: Re: [RFC][PATCH 12/15] videobuf2: add begin/end cpu_access callbacks
 to dma-sg
Message-ID: <20200122063714.GA14881@google.com>
References: <20191217032034.54897-1-senozhatsky@chromium.org>
 <20191217032034.54897-13-senozhatsky@chromium.org>
 <1c5198dc-db4e-47d6-0d8b-259fbbb6372f@xs4all.nl>
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On (20/01/10 11:13), Hans Verkuil wrote:
> On 12/17/19 4:20 AM, Sergey Senozhatsky wrote:
> > Provide begin_cpu_access() and end_cpu_access() dma_buf_ops
> > callbacks for cache synchronisation on exported buffers.
> > 
> > Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> > ---
> >  .../media/common/videobuf2/videobuf2-dma-sg.c | 22 +++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> > 
> > diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> > index 6db60e9d5183..bfc99a0cb7b9 100644
> > --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> > +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> > @@ -470,6 +470,26 @@ static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
> >  	vb2_dma_sg_put(dbuf->priv);
> >  }
> >  
> 
> There is no corresponding vb2_sg_buffer_consistent function here.
> 
> Looking more closely I see that vb2_dma_sg_alloc doesn't pass the dma_attrs
> argument to dma_map_sg_attrs, thus V4L2_FLAG_MEMORY_NON_CONSISTENT has no
> effect on dma-sg buffers.
> 
> Is there a reason why dma_attrs isn't passed on to dma_map_sg_attrs()?

Laziness.

> I suspect it was just laziness in the past, and that it should be wired
> up, just as for dma-contig.

OK, I can include it into v2.

	-ss