From: Junghak Sung <jh1009.sung@samsung.com>
To: Hans Verkuil <hverkuil@xs4all.nl>, linux-media@vger.kernel.org
Cc: mchehab@osg.samsung.com, sangbae90.lee@samsung.com,
inki.dae@samsung.com, nenggun.kim@samsung.com,
sw0312.kim@samsung.com
Subject: Re: [RFC PATCH 0/3] Refactoring Videobuf2 for common use
Date: Tue, 23 Jun 2015 09:48:01 +0900 [thread overview]
Message-ID: <5588ACC1.8010408@samsung.com> (raw)
In-Reply-To: <557AB99C.6030905@xs4all.nl>
Hi Hans,
Thank you for your review.
I reply to your comments. See below.
Regards,
Junghak
On 06/12/2015 07:51 PM, Hans Verkuil wrote:
> Hi Junghak,
>
> On 06/08/2015 03:35 PM, Junghak Sung wrote:
>> Hello everybody,
>>
>> This patch series refactories exsiting Videobuf2, so that not only V4L2
>> but also other frameworks can use it to manage buffer and utilize
>> queue.
>>
>> I would separate existing Videobuf2-core framework into two parts - common
>> and v4l2-specific part. This work is as follows :
>>
>> 1. Separate existing vb2_buffer structure into common buffer and
>> v4l2-specific parts by removing v4l2-specific members and
>> embedding it into vb2_v4l2_buffer structure like this:
>>
>> struct vb2_v4l2_buffer {
>> struct vb2_buffer vb2;
>> struct v4l2_buffer v4l2_buf;
>> struct v4l2_plane v4l2_planes[VIDEO_MAX_PLANES];
>> };
>>
>> 2. Abstract the v4l2-specific elements, and specify them when the device
>> drives use them. For example, vb2_v4l2_buffer structure can be abstracted
>> by vb2_buffer structure, and device drivers can get framework-specific
>> object such as vb2_v4l2_buffer by using container_of().
>>
>> 3. Separate VB2-core framework into real VB2-core and v4l2-specific part.
>> This means that it moves V4L2-specific parts of VB2-core to v4l2-specific
>> part because current VB2-core framework has some codes dependent of V4L2.
>> As a result, we will have two VB2 files - videobuf2-core.c and
>> videobuf2-v4l2.c.
>>
>> Why do we try to make the VB2 framework to be common?
>>
>> As you may know, current DVB framework uses ringbuffer mechanism to demux
>> MPEG-2 TS data and pass it to userspace. However, this mechanism requires
>> extra memory copy because DVB framework provides only read() system call for
>> application - read() system call copies the kernel data to user-space buffer.
>>
>> So if we can use VB2 framework which supports streaming I/O and buffer
>> sharing mechanism, then we could enhance existing DVB framework by removing
>> the extra memory copy - with VB2 framework, application can access the kernel
>> data directly through mmap system call.
>>
>> This patch series is the first step for it.
>>
>> We have a plan for this work as follows:
>>
>> 1. Separate existing VB2 framework into three parts - VB2 common, VB2-v4l2,
>> and VB2-dvb. Of course, this change should not affect other v4l2-based
>> device drivers. This patch series includes some parts of this step.
>>
>> 2. Add new APIs for DVB streaming I/O. These APIs will be implemented
>> in VB2-dvb framework. So, we can remove unnecessary memory copy between
>> kernel-space and user-space by using these new APIs.
>> However, we leaves legacy interfaces as-is for backward compatibility.
>>
>> We are working on this project with Mauro and have a discussion with him
>> on IRC channel weekly. Nowaday, we are discussing more detailed DVB user
>> scenario for streaming I/O.
>>
>> The final goal of this project is to enhance current DVB framework.
>> The first mission is to achieve zero-copy functionality between kernel-space
>> and user-space with mmap system call. More missions are under consideration:
>> i.e., we could share the buffer not only between kernel-space and user-space
>> but also between devices - demux, hw video codec - by exporting a buffer
>> to dmabuf fd with VB2 framework.
>>
>> Any suggestions and comments are welcome.
> I've tried to review it, but in the current form it is too hard to do. It's not
> helped by the fact that patch 2 didn't make it to the mailinglist. It might
> be better to just split up such large patches and make a note that the pull
> request will combine the two (or more) patches into one.
I agree with your opinion that the patches should be rework to be
more easier to review. I will try to split up the patches and resend it.
> BTW, I fully agree with what you want to do, where I am having trouble is
> verifying that nothing breaks and in the details of the vb2 API changes.
>
> Can you make a new patch series that only shows the changes to the videobuf2
> sources and headers, so without all the driver changes? The driver changes
> are automatically checked by the compiler when you build the drivers, so I
> believe that that's correct (I hope :-) ).
>
> Also try to split it up in smaller pieces. I had the feeling that you combined
> multiple but otherwise independent changes in one patch. The vb2 framework is
> an important piece of code, and I want to be confident about the changes made.
>
> Regarding the split into core and v4l2 sources/headers: I've been thinking about
> this a bit more, and what would probably make reviewing easiest is if you start
> off with making a simple videobuf2-v4l2.h header that just includes core.h and
> slowly move the v4l2-specific parts from videobuf2-core.h to videobuf2-v4l2.h.
>
> And do the same with videobuf2-v4l2.c: start off with an empty source and move
> code from core.c to v4l2.c whenever a v4l2-specific part migrates.
That's a good point. I think I have made these patches too hastily.
As your comment, I will split the patch into two or more pieces.
The first is just renaming videobuf2-core.[ch] to videobuf2-v4l2.[ch].
> Another note: I noticed that the queue_setup op was changed so the v4l2_format
> argument became a void *. I do not think that that is the right approach since
> we lose strong typing.
>
> I wonder if v4l2-specific queue ops should be introduced. I'm not sure how that
> would work out, but I think we can look at that for the next round of patches.
OK, I will try to find out more reasonable way to make it commonly (not
v4l2-specific)
without changing the v4l2-specivic queue ops.
> Regards,
>
> Hans
>
>> Best regards,
>> Junghak
>>
>> Junghak Sung (3):
>> modify the vb2_buffer structure for common video buffer and make
>> struct vb2_v4l2_buffer
>> move struct vb2_queue to common and apply the changes related with
>> that Signed-off-by: Junghak Sung <jh1009.sung@samsung.com>
>> make vb2-core part with not v4l2-specific elements
>>
>> Documentation/video4linux/v4l2-pci-skeleton.c | 16 +-
>> drivers/media/dvb-frontends/rtl2832_sdr.c | 13 +-
>> drivers/media/pci/cx23885/cx23885-417.c | 13 +-
>> drivers/media/pci/cx23885/cx23885-core.c | 4 +-
>> drivers/media/pci/cx23885/cx23885-dvb.c | 12 +-
>> drivers/media/pci/cx23885/cx23885-vbi.c | 17 +-
>> drivers/media/pci/cx23885/cx23885-video.c | 19 +-
>> drivers/media/pci/cx23885/cx23885.h | 2 +-
>> drivers/media/pci/cx25821/cx25821-video.c | 20 +-
>> drivers/media/pci/cx25821/cx25821.h | 2 +-
>> drivers/media/pci/cx88/cx88-blackbird.c | 15 +-
>> drivers/media/pci/cx88/cx88-core.c | 2 +-
>> drivers/media/pci/cx88/cx88-dvb.c | 13 +-
>> drivers/media/pci/cx88/cx88-mpeg.c | 2 +-
>> drivers/media/pci/cx88/cx88-vbi.c | 17 +-
>> drivers/media/pci/cx88/cx88-video.c | 17 +-
>> drivers/media/pci/cx88/cx88.h | 2 +-
>> drivers/media/pci/saa7134/saa7134-core.c | 4 +-
>> drivers/media/pci/saa7134/saa7134-ts.c | 28 +-
>> drivers/media/pci/saa7134/saa7134-vbi.c | 22 +-
>> drivers/media/pci/saa7134/saa7134-video.c | 17 +-
>> drivers/media/pci/saa7134/saa7134.h | 8 +-
>> drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c | 19 +-
>> drivers/media/pci/solo6x10/solo6x10-v4l2.c | 11 +-
>> drivers/media/pci/solo6x10/solo6x10.h | 4 +-
>> drivers/media/pci/sta2x11/sta2x11_vip.c | 24 +-
>> drivers/media/pci/tw68/tw68-video.c | 20 +-
>> drivers/media/pci/tw68/tw68.h | 2 +-
>> drivers/media/platform/am437x/am437x-vpfe.c | 33 +-
>> drivers/media/platform/am437x/am437x-vpfe.h | 2 +-
>> drivers/media/platform/blackfin/bfin_capture.c | 30 +-
>> drivers/media/platform/coda/coda-bit.c | 20 +-
>> drivers/media/platform/coda/coda-common.c | 28 +-
>> drivers/media/platform/coda/coda-jpeg.c | 2 +-
>> drivers/media/platform/coda/coda.h | 6 +-
>> drivers/media/platform/davinci/vpbe_display.c | 25 +-
>> drivers/media/platform/davinci/vpif_capture.c | 30 +-
>> drivers/media/platform/davinci/vpif_capture.h | 2 +-
>> drivers/media/platform/davinci/vpif_display.c | 34 +-
>> drivers/media/platform/davinci/vpif_display.h | 6 +-
>> drivers/media/platform/exynos-gsc/gsc-core.c | 2 +-
>> drivers/media/platform/exynos-gsc/gsc-core.h | 6 +-
>> drivers/media/platform/exynos-gsc/gsc-m2m.c | 12 +-
>> drivers/media/platform/exynos4-is/fimc-capture.c | 23 +-
>> drivers/media/platform/exynos4-is/fimc-core.c | 4 +-
>> drivers/media/platform/exynos4-is/fimc-core.h | 6 +-
>> drivers/media/platform/exynos4-is/fimc-is.h | 2 +-
>> drivers/media/platform/exynos4-is/fimc-isp-video.c | 25 +-
>> drivers/media/platform/exynos4-is/fimc-isp-video.h | 2 +-
>> drivers/media/platform/exynos4-is/fimc-isp.h | 4 +-
>> drivers/media/platform/exynos4-is/fimc-lite.c | 25 +-
>> drivers/media/platform/exynos4-is/fimc-lite.h | 4 +-
>> drivers/media/platform/exynos4-is/fimc-m2m.c | 14 +-
>> drivers/media/platform/m2m-deinterlace.c | 16 +-
>> drivers/media/platform/marvell-ccic/mcam-core.c | 26 +-
>> drivers/media/platform/marvell-ccic/mcam-core.h | 2 +-
>> drivers/media/platform/mx2_emmaprp.c | 16 +-
>> drivers/media/platform/omap3isp/ispvideo.c | 24 +-
>> drivers/media/platform/omap3isp/ispvideo.h | 4 +-
>> drivers/media/platform/s3c-camif/camif-capture.c | 23 +-
>> drivers/media/platform/s3c-camif/camif-core.c | 2 +-
>> drivers/media/platform/s3c-camif/camif-core.h | 4 +-
>> drivers/media/platform/s5p-g2d/g2d.c | 14 +-
>> drivers/media/platform/s5p-jpeg/jpeg-core.c | 34 +-
>> drivers/media/platform/s5p-mfc/s5p_mfc.c | 14 +-
>> drivers/media/platform/s5p-mfc/s5p_mfc_common.h | 4 +-
>> drivers/media/platform/s5p-mfc/s5p_mfc_dec.c | 36 +-
>> drivers/media/platform/s5p-mfc/s5p_mfc_enc.c | 57 +-
>> drivers/media/platform/s5p-mfc/s5p_mfc_opr_v5.c | 4 +-
>> drivers/media/platform/s5p-mfc/s5p_mfc_opr_v6.c | 4 +-
>> drivers/media/platform/s5p-tv/mixer.h | 4 +-
>> drivers/media/platform/s5p-tv/mixer_reg.c | 2 +-
>> drivers/media/platform/s5p-tv/mixer_video.c | 11 +-
>> drivers/media/platform/sh_veu.c | 25 +-
>> drivers/media/platform/soc_camera/atmel-isi.c | 26 +-
>> drivers/media/platform/soc_camera/mx2_camera.c | 41 +-
>> drivers/media/platform/soc_camera/mx3_camera.c | 34 +-
>> drivers/media/platform/soc_camera/rcar_vin.c | 30 +-
>> .../platform/soc_camera/sh_mobile_ceu_camera.c | 47 +-
>> drivers/media/platform/soc_camera/soc_camera.c | 2 +-
>> drivers/media/platform/ti-vpe/vpe.c | 30 +-
>> drivers/media/platform/vim2m.c | 28 +-
>> drivers/media/platform/vivid/vivid-core.h | 4 +-
>> drivers/media/platform/vivid/vivid-kthread-cap.c | 8 +-
>> drivers/media/platform/vivid/vivid-kthread-out.c | 8 +-
>> drivers/media/platform/vivid/vivid-sdr-cap.c | 18 +-
>> drivers/media/platform/vivid/vivid-vbi-cap.c | 14 +-
>> drivers/media/platform/vivid/vivid-vbi-out.c | 14 +-
>> drivers/media/platform/vivid/vivid-vid-cap.c | 24 +-
>> drivers/media/platform/vivid/vivid-vid-out.c | 21 +-
>> drivers/media/platform/vsp1/vsp1_rpf.c | 4 +-
>> drivers/media/platform/vsp1/vsp1_video.c | 20 +-
>> drivers/media/platform/vsp1/vsp1_video.h | 6 +-
>> drivers/media/platform/vsp1/vsp1_wpf.c | 4 +-
>> drivers/media/usb/airspy/airspy.c | 15 +-
>> drivers/media/usb/au0828/au0828-vbi.c | 17 +-
>> drivers/media/usb/au0828/au0828-video.c | 29 +-
>> drivers/media/usb/au0828/au0828.h | 2 +-
>> drivers/media/usb/em28xx/em28xx-vbi.c | 15 +-
>> drivers/media/usb/em28xx/em28xx-video.c | 30 +-
>> drivers/media/usb/em28xx/em28xx.h | 2 +-
>> drivers/media/usb/go7007/go7007-driver.c | 2 +-
>> drivers/media/usb/go7007/go7007-priv.h | 4 +-
>> drivers/media/usb/go7007/go7007-v4l2.c | 15 +-
>> drivers/media/usb/hackrf/hackrf.c | 13 +-
>> drivers/media/usb/msi2500/msi2500.c | 13 +-
>> drivers/media/usb/pwc/pwc-if.c | 26 +-
>> drivers/media/usb/pwc/pwc.h | 2 +-
>> drivers/media/usb/s2255/s2255drv.c | 16 +-
>> drivers/media/usb/stk1160/stk1160-v4l.c | 15 +-
>> drivers/media/usb/stk1160/stk1160-video.c | 2 +-
>> drivers/media/usb/stk1160/stk1160.h | 4 +-
>> drivers/media/usb/usbtv/usbtv-video.c | 11 +-
>> drivers/media/usb/usbtv/usbtv.h | 2 +-
>> drivers/media/usb/uvc/uvc_queue.c | 32 +-
>> drivers/media/usb/uvc/uvcvideo.h | 4 +-
>> drivers/media/v4l2-core/Makefile | 2 +-
>> drivers/media/v4l2-core/v4l2-ioctl.c | 2 +-
>> drivers/media/v4l2-core/v4l2-mem2mem.c | 8 +-
>> drivers/media/v4l2-core/videobuf2-core.c | 1888 ++------------------
>> drivers/media/v4l2-core/videobuf2-dma-contig.c | 2 +-
>> drivers/media/v4l2-core/videobuf2-dma-sg.c | 2 +-
>> drivers/media/v4l2-core/videobuf2-dvb.c | 2 +-
>> drivers/media/v4l2-core/videobuf2-memops.c | 2 +-
>> drivers/media/v4l2-core/videobuf2-v4l2.c | 1878 +++++++++++++++++++
>> drivers/media/v4l2-core/videobuf2-vmalloc.c | 2 +-
>> drivers/staging/media/davinci_vpfe/vpfe_video.c | 30 +-
>> drivers/staging/media/davinci_vpfe/vpfe_video.h | 2 +-
>> drivers/staging/media/dt3155v4l/dt3155v4l.c | 14 +-
>> drivers/staging/media/dt3155v4l/dt3155v4l.h | 2 +-
>> drivers/staging/media/omap4iss/iss_video.c | 16 +-
>> drivers/staging/media/omap4iss/iss_video.h | 4 +-
>> drivers/usb/gadget/function/uvc_queue.c | 14 +-
>> drivers/usb/gadget/function/uvc_queue.h | 4 +-
>> include/media/davinci/vpbe_display.h | 2 +-
>> include/media/soc_camera.h | 2 +-
>> include/media/v4l2-mem2mem.h | 10 +-
>> include/media/videobuf2-core.h | 235 ++-
>> include/media/videobuf2-dma-contig.h | 6 +-
>> include/media/videobuf2-dma-sg.h | 6 +-
>> include/media/videobuf2-dvb.h | 2 +-
>> include/media/videobuf2-memops.h | 2 +-
>> include/media/videobuf2-v4l2.h | 139 ++
>> include/media/videobuf2-vmalloc.h | 2 +-
>> 144 files changed, 3290 insertions(+), 2662 deletions(-)
>> create mode 100644 drivers/media/v4l2-core/videobuf2-v4l2.c
>> create mode 100644 include/media/videobuf2-v4l2.h
>>
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next prev parent reply other threads:[~2015-06-23 0:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-08 13:35 [RFC PATCH 0/3] Refactoring Videobuf2 for common use Junghak Sung
2015-06-08 13:35 ` [RFC PATCH 1/3] modify the vb2_buffer structure for common video buffer and make struct vb2_v4l2_buffer Junghak Sung
2015-06-12 9:58 ` Hans Verkuil
2015-06-12 10:09 ` Hans Verkuil
2015-06-17 11:55 ` Mauro Carvalho Chehab
2015-06-17 12:27 ` Mauro Carvalho Chehab
2015-06-23 1:11 ` Junghak Sung
2015-06-08 13:35 ` [RFC PATCH 3/3] make vb2-core part with not v4l2-specific elements Junghak Sung
2015-06-08 14:42 ` [RFC PATCH 0/3] Refactoring Videobuf2 for common use Hans Verkuil
2015-06-08 17:39 ` Mauro Carvalho Chehab
2015-06-09 1:41 ` Junghak Sung
2015-06-12 10:51 ` Hans Verkuil
2015-06-23 0:48 ` Junghak Sung [this message]
[not found] ` <1433770535-21143-3-git-send-email-jh1009.sung@samsung.com>
2015-06-17 13:16 ` [RFC PATCH 2/3] make struct vb2_queue to common and apply the changes related with that Mauro Carvalho Chehab
2015-06-23 1:33 ` Junghak Sung
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