From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-iy0-f174.google.com ([209.85.210.174]:43304 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755734Ab2AXLHu (ORCPT ); Tue, 24 Jan 2012 06:07:50 -0500 Received: by iacb35 with SMTP id b35so5221998iac.19 for ; Tue, 24 Jan 2012 03:07:49 -0800 (PST) Message-ID: <4F1E9100.90306@gmail.com> Date: Tue, 24 Jan 2012 16:37:44 +0530 From: Subash Patel MIME-Version: 1.0 To: Tomasz Stanislawski CC: linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, pawel@osciak.com, sumit.semwal@ti.com, jesse.barker@linaro.org, kyungmin.park@samsung.com, daniel@ffwll.ch Subject: Re: [Linaro-mm-sig] [PATCH 05/10] v4l: add buffer exporting via dmabuf References: <1327326675-8431-1-git-send-email-t.stanislaws@samsung.com> <1327326675-8431-6-git-send-email-t.stanislaws@samsung.com> In-Reply-To: <1327326675-8431-6-git-send-email-t.stanislaws@samsung.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hello Thomasz, Instead of adding another IOCTL to query the file-descriptor in user-space, why dont we extend the existing ones in v4l2/vb2? When the memory type set is V4L2_MEMORY_DMABUF, call to VIDIOC_REQBUFS /VIDIOC_QUERYBUF from driver can take/return the fd. We will need to add another attribute to struct v4l2_requestbuffers for this. struct v4l2_requestbuffers { ... __u32 buf_fd; }; The application requesting buffer would set it to -1, and will receive the fd's when it calls the vb2_querybuf. In the same way, application which is trying to attach to already allocated buffer will set this to valid fd when it calls vidioc_reqbuf, and in vb2_reqbuf depending on the memory type, this can be checked and used to attach with the dma_buf for the respective buffer. Ofcourse, this requires changes in vb2_reqbufs and vb2_querybuf similar to what you did in vb2_expbufs. Will there be any issues in such an approach? Regards, Subash On 01/23/2012 07:21 PM, Tomasz Stanislawski wrote: > This patch adds extension to V4L2 api. It allow to export a mmap buffer as file > descriptor. New ioctl VIDIOC_EXPBUF is added. It takes a buffer offset used by > mmap and return a file descriptor on success. > > Signed-off-by: Tomasz Stanislawski > Signed-off-by: Kyungmin Park > --- > drivers/media/video/v4l2-compat-ioctl32.c | 1 + > drivers/media/video/v4l2-ioctl.c | 11 +++++++++++ > include/linux/videodev2.h | 1 + > include/media/v4l2-ioctl.h | 1 + > 4 files changed, 14 insertions(+), 0 deletions(-) > > diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c > index c68531b..0f18b5e 100644 > --- a/drivers/media/video/v4l2-compat-ioctl32.c > +++ b/drivers/media/video/v4l2-compat-ioctl32.c > @@ -954,6 +954,7 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int cmd, unsigned long arg) > case VIDIOC_S_FBUF32: > case VIDIOC_OVERLAY32: > case VIDIOC_QBUF32: > + case VIDIOC_EXPBUF: > case VIDIOC_DQBUF32: > case VIDIOC_STREAMON32: > case VIDIOC_STREAMOFF32: > diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c > index e1da8fc..cb29e00 100644 > --- a/drivers/media/video/v4l2-ioctl.c > +++ b/drivers/media/video/v4l2-ioctl.c > @@ -207,6 +207,7 @@ static const char *v4l2_ioctls[] = { > [_IOC_NR(VIDIOC_S_FBUF)] = "VIDIOC_S_FBUF", > [_IOC_NR(VIDIOC_OVERLAY)] = "VIDIOC_OVERLAY", > [_IOC_NR(VIDIOC_QBUF)] = "VIDIOC_QBUF", > + [_IOC_NR(VIDIOC_EXPBUF)] = "VIDIOC_EXPBUF", > [_IOC_NR(VIDIOC_DQBUF)] = "VIDIOC_DQBUF", > [_IOC_NR(VIDIOC_STREAMON)] = "VIDIOC_STREAMON", > [_IOC_NR(VIDIOC_STREAMOFF)] = "VIDIOC_STREAMOFF", > @@ -932,6 +933,16 @@ static long __video_do_ioctl(struct file *file, > dbgbuf(cmd, vfd, p); > break; > } > + case VIDIOC_EXPBUF: > + { > + unsigned int *p = arg; > + > + if (!ops->vidioc_expbuf) > + break; > + > + ret = ops->vidioc_expbuf(file, fh, *p); > + break; > + } > case VIDIOC_DQBUF: > { > struct v4l2_buffer *p = arg; > diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h > index 3c0ade1..448fbed 100644 > --- a/include/linux/videodev2.h > +++ b/include/linux/videodev2.h > @@ -2183,6 +2183,7 @@ struct v4l2_create_buffers { > #define VIDIOC_S_FBUF _IOW('V', 11, struct v4l2_framebuffer) > #define VIDIOC_OVERLAY _IOW('V', 14, int) > #define VIDIOC_QBUF _IOWR('V', 15, struct v4l2_buffer) > +#define VIDIOC_EXPBUF _IOWR('V', 16, __u32) > #define VIDIOC_DQBUF _IOWR('V', 17, struct v4l2_buffer) > #define VIDIOC_STREAMON _IOW('V', 18, int) > #define VIDIOC_STREAMOFF _IOW('V', 19, int) > diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h > index 4d1c74a..8201546 100644 > --- a/include/media/v4l2-ioctl.h > +++ b/include/media/v4l2-ioctl.h > @@ -120,6 +120,7 @@ struct v4l2_ioctl_ops { > int (*vidioc_reqbufs) (struct file *file, void *fh, struct v4l2_requestbuffers *b); > int (*vidioc_querybuf)(struct file *file, void *fh, struct v4l2_buffer *b); > int (*vidioc_qbuf) (struct file *file, void *fh, struct v4l2_buffer *b); > + int (*vidioc_expbuf) (struct file *file, void *fh, __u32 offset); > int (*vidioc_dqbuf) (struct file *file, void *fh, struct v4l2_buffer *b); > > int (*vidioc_create_bufs)(struct file *file, void *fh, struct v4l2_create_buffers *b);