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Date:   Mon, 26 Jul 2021 10:40:14 +0900
From:   Sergey Senozhatsky <senozhatsky@chromium.org>
To:     Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Tomasz Figa <tfiga@chromium.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Ricardo Ribalda <ribalda@chromium.org>,
        Christoph Hellwig <hch@lst.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Collabora Kernel ML <kernel@collabora.com>
Subject: Re: [PATCHv3 7/8] videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT
 flag
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References: <20210709092027.1050834-1-senozhatsky@chromium.org>
 <20210709092027.1050834-8-senozhatsky@chromium.org>
 <0c89ef1e-8abb-8749-bbce-c7e5a2e2f304@collabora.com>
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On (21/07/22 19:33), Dafna Hirschfeld wrote:
[..]
> >   int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
> >   {
> >   	int ret = vb2_verify_memory_type(q, req->memory, req->type);
> > +	u32 flags = req->flags;
> >   	fill_buf_caps(q, &req->capabilities);
> > -	return ret ? ret : vb2_core_reqbufs(q, req->memory, 0, &req->count);
> > +	validate_memory_flags(q, req->memory, &flags);
> > +	req->flags = flags;
> 
> you can do instead
> 
> validate_memory_flags(q, req->memory, &req->flags);

->flags are u32 for create-bufs and u8 for reqi-bufs. So `*flags = <value>`
can write to ->reserved[] for req-bufs (if the value is huge enough).