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[209.85.221.42]) by smtp.gmail.com with ESMTPSA id r15sm2267141edw.46.2021.07.25.21.22.23 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 25 Jul 2021 21:22:24 -0700 (PDT) Received: by mail-wr1-f42.google.com with SMTP id l4so9446610wrs.4 for ; Sun, 25 Jul 2021 21:22:23 -0700 (PDT) X-Received: by 2002:a05:6000:548:: with SMTP id b8mr17286012wrf.159.1627273343336; Sun, 25 Jul 2021 21:22:23 -0700 (PDT) MIME-Version: 1.0 References: <20210709092027.1050834-1-senozhatsky@chromium.org> <20210709092027.1050834-8-senozhatsky@chromium.org> <0c89ef1e-8abb-8749-bbce-c7e5a2e2f304@collabora.com> In-Reply-To: From: Tomasz Figa Date: Mon, 26 Jul 2021 13:22:12 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCHv3 7/8] videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT flag To: Sergey Senozhatsky Cc: Dafna Hirschfeld , Hans Verkuil , Ricardo Ribalda , Christoph Hellwig , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Collabora Kernel ML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 26, 2021 at 1:20 PM Sergey Senozhatsky wrote: > > On (21/07/26 13:05), Sergey Senozhatsky wrote: > > On (21/07/26 10:40), Sergey Senozhatsky wrote: > > > 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 = ` > > > can write to ->reserved[] for req-bufs (if the value is huge enough). > > > > I guess ->flags can become u8 for both create-bufs and req-bufs. > > We had ->flags in both structs as u32, but then decided to leave > > some reserved[] space in req-bufs and switched to u8 there. > > Something like this > > --- > > diff --git a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst > index a048a9f6b7b6..cf633b5a4919 100644 > --- a/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst > +++ b/Documentation/userspace-api/media/v4l/vidioc-create-bufs.rst > @@ -112,13 +112,13 @@ than the number requested. > other changes, then set ``count`` to 0, ``memory`` to > ``V4L2_MEMORY_MMAP`` and ``format.type`` to the buffer type. > > - * - __u32 > + * - __u8 > - ``flags`` > - Specifies additional buffer management attributes. > See :ref:`memory-flags`. > > - * - __u32 > - - ``reserved``\ [6] > + * - __u8 > + - ``reserved``\ [27] > - A place holder for future extensions. Drivers and applications > must set the array to zero. > > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c > index 6edf4508c636..2ae949ec0afa 100644 > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c > @@ -694,7 +694,7 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps) > > static void validate_memory_flags(struct vb2_queue *q, > int memory, > - u32 *flags) > + u8 *flags) > { > if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) { > /* > @@ -711,11 +711,9 @@ static void validate_memory_flags(struct vb2_queue *q, > 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); > - validate_memory_flags(q, req->memory, &flags); > - req->flags = flags; > + validate_memory_flags(q, req->memory, &req->flags); > return ret ? ret : vb2_core_reqbufs(q, req->memory, > req->flags, &req->count); > } > @@ -990,11 +988,9 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv, > { > struct video_device *vdev = video_devdata(file); > int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type); > - u32 flags = p->flags; > > fill_buf_caps(vdev->queue, &p->capabilities); > - validate_memory_flags(vdev->queue, p->memory, &flags); > - p->flags = flags; > + validate_memory_flags(vdev->queue, p->memory, &p->flags); > if (res) > return res; > if (vb2_queue_is_busy(vdev, file)) > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > index 7973aa0465d2..ad4f7cee53f2 100644 > --- a/include/uapi/linux/videodev2.h > +++ b/include/uapi/linux/videodev2.h > @@ -2513,8 +2513,8 @@ struct v4l2_create_buffers { > __u32 memory; > struct v4l2_format format; > __u32 capabilities; > - __u32 flags; > - __u32 reserved[6]; > + __u8 flags; > + __u8 reserved[27]; > }; > > /* I don't think we want this UABI churn anymore for a trivial simplification in the implementation. Best regards, Tomasz