From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Steve Longerbeam <slongerbeam@gmail.com>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>,
hverkuil@xs4all.nl,
Steve Longerbeam <steve_longerbeam@mentor.com>,
linux-media@vger.kernel.org, p.zabel@pengutronix.de,
Sakari Ailus <sakari.ailus@linux.intel.com>
Subject: vb2 queue_setup documentation clarification (was "Re: [PATCH v3 00/24] i.MX Media Driver")
Date: Fri, 03 Feb 2017 16:21:34 +0200 [thread overview]
Message-ID: <1600727.suTjUfaXG8@avalon> (raw)
In-Reply-To: <2e1cf096-ecb8-ba3d-a554-f4cc6999ed4e@gmail.com>
Hi Steve,
(stripping the CC list a bit and adding Sakari Ailus)
On Thursday 02 Feb 2017 11:12:41 Steve Longerbeam wrote:
> On 02/02/2017 10:58 AM, Russell King - ARM Linux wrote:
[snip]
> > It seems to me that if you don't take account of the existing queue
> > size, your camif_queue_setup() has the side effect that each time
> > either of these are called. Hence, the vb2 queue increases by the
> > same amount each time, which is probably what you don't want.
> >
> > The documentation on queue_setup() leaves much to be desired:
> > * @queue_setup: called from VIDIOC_REQBUFS() and VIDIOC_CREATE_BUFS()
> > * handlers before memory allocation. It can be called
> > * twice: if the original number of requested buffers
> > * could not be allocated, then it will be called a
> > * second time with the actually allocated number of
> > * buffers to verify if that is OK.
> > * The driver should return the required number of buffers
> > * in \*num_buffers, the required number of planes per
> > * buffer in \*num_planes, the size of each plane should be
> > * set in the sizes\[\] array and optional per-plane
> > * allocator specific device in the alloc_devs\[\] array.
> > * When called from VIDIOC_REQBUFS,() \*num_planes == 0,
> > * the driver has to use the currently configured format to
> > * determine the plane sizes and \*num_buffers is the total
> > * number of buffers that are being allocated. When called
> > * from VIDIOC_CREATE_BUFS,() \*num_planes != 0 and it
> > * describes the requested number of planes and sizes\[\]
> > * contains the requested plane sizes. If either
> > * \*num_planes or the requested sizes are invalid callback
> > * must return %-EINVAL. In this case \*num_buffers are
> > * being allocated additionally to q->num_buffers.
> >
> > That's really really ambiguous, because the "In this case" part doesn't
> > really tell you which case it's talking about - but it seems to me looking
> > at the code that it's referring to the VIDIOC_CREATE_BUFS case.
>
> Yes, I caught this when adding fixes from v4l2-compliance testing, which
> is not part of the version 3 driver. I agree it is a confusing API. When
> called from VIDIOC_CREATE_BUFS (indicated by *num_planes != 0),
> *num_buffers is supposed to be requested buffers _in addition_ to
> already requested q->num_buffers, which is important info and
> should be emphasized a little more than the "oh by the way" fashion
> in the prototype description, IMHO.
Hans, Sakari, any opinion ?
[snip]
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2017-02-03 14:21 UTC|newest]
Thread overview: 190+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-07 2:11 [PATCH v3 00/24] i.MX Media Driver Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 01/24] [media] dt-bindings: Add bindings for i.MX media driver Steve Longerbeam
2017-01-13 11:55 ` Philipp Zabel
2017-01-13 19:03 ` Steve Longerbeam
2017-01-16 12:09 ` Philipp Zabel
2017-01-16 17:13 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 02/24] ARM: dts: imx6qdl: Add compatible, clocks, irqs to MIPI CSI-2 node Steve Longerbeam
2017-01-13 11:57 ` Philipp Zabel
2017-01-13 22:40 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 03/24] ARM: dts: imx6qdl: Add mipi_ipu1/2 multiplexers, mipi_csi, and their connections Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 04/24] ARM: dts: imx6qdl: add media device Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 05/24] ARM: dts: imx6qdl-sabrelite: remove erratum ERR006687 workaround Steve Longerbeam
2017-01-13 11:59 ` Philipp Zabel
2017-01-07 2:11 ` [PATCH v3 06/24] ARM: dts: imx6-sabrelite: add OV5642 and OV5640 camera sensors Steve Longerbeam
2017-01-13 12:03 ` Philipp Zabel
2017-01-13 23:04 ` Steve Longerbeam
2017-01-16 12:55 ` Philipp Zabel
2017-01-16 17:15 ` Steve Longerbeam
2017-02-05 15:17 ` Laurent Pinchart
2017-01-30 22:28 ` Russell King - ARM Linux
2017-01-30 22:51 ` Russell King - ARM Linux
2017-02-05 15:24 ` Laurent Pinchart
2017-02-05 15:37 ` Russell King - ARM Linux
2017-01-07 2:11 ` [PATCH v3 07/24] ARM: dts: imx6-sabresd: " Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 08/24] ARM: dts: imx6-sabreauto: create i2cmux for i2c3 Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 09/24] ARM: dts: imx6-sabreauto: add reset-gpios property for max7310_b Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 10/24] ARM: dts: imx6-sabreauto: add pinctrl for gpt input capture Steve Longerbeam
2017-01-12 19:37 ` Tim Harvey
2017-01-12 23:40 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 11/24] ARM: dts: imx6-sabreauto: add the ADV7180 video decoder Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 12/24] add mux and video interface bridge entity functions Steve Longerbeam
2017-01-20 13:56 ` Hans Verkuil
2017-02-05 15:36 ` Laurent Pinchart
2017-02-06 10:27 ` Philipp Zabel
2017-01-07 2:11 ` [PATCH v3 13/24] platform: add video-multiplexer subdevice driver Steve Longerbeam
2017-01-10 5:35 ` Rob Herring
2017-01-20 14:03 ` Hans Verkuil
2017-01-24 12:02 ` Philipp Zabel
2017-01-25 2:07 ` Steve Longerbeam
2017-02-05 15:48 ` Laurent Pinchart
2017-02-06 9:50 ` Hans Verkuil
2017-02-06 22:33 ` Laurent Pinchart
2017-02-06 23:10 ` Steve Longerbeam
2017-02-07 10:26 ` Laurent Pinchart
2017-02-07 10:41 ` Philipp Zabel
2017-02-07 14:11 ` Laurent Pinchart
2017-02-07 13:36 ` Benoit Parrot
2017-02-07 20:50 ` Sakari Ailus
2017-02-07 23:04 ` Laurent Pinchart
2017-01-24 12:44 ` Javier Martinez Canillas
2017-01-26 1:22 ` Steve Longerbeam
2017-02-07 20:46 ` Sakari Ailus
2017-02-08 9:47 ` Philipp Zabel
2017-02-08 10:05 ` Laurent Pinchart
2017-01-07 2:11 ` [PATCH v3 14/24] UAPI: Add media UAPI Kbuild file Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 15/24] media: Add userspace header file for i.MX Steve Longerbeam
2017-01-13 12:05 ` Philipp Zabel
2017-01-13 23:13 ` Steve Longerbeam
2017-02-05 15:50 ` Laurent Pinchart
2017-01-07 2:11 ` [PATCH v3 16/24] media: Add i.MX media core driver Steve Longerbeam
2017-01-13 15:20 ` Philipp Zabel
2017-01-14 22:46 ` Steve Longerbeam
2017-01-16 13:47 ` Philipp Zabel
2017-01-23 2:31 ` Steve Longerbeam
2017-01-23 11:13 ` Philipp Zabel
2017-01-24 1:38 ` Steve Longerbeam
2017-01-24 1:45 ` Steve Longerbeam
2017-01-24 11:37 ` Philipp Zabel
2017-01-30 15:28 ` Russell King - ARM Linux
[not found] ` <2b1d2418-1ad4-6373-cb07-c3aeab48187f@gmail.com>
2017-01-19 1:44 ` Steve Longerbeam
2017-01-24 11:39 ` Philipp Zabel
2017-01-30 22:29 ` Russell King - ARM Linux
2017-02-02 22:44 ` Russell King - ARM Linux
2017-02-02 22:50 ` Russell King - ARM Linux
2017-02-07 1:54 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 17/24] media: imx: Add CSI subdev driver Steve Longerbeam
2017-01-16 15:03 ` Philipp Zabel
2017-01-16 21:15 ` Steve Longerbeam
2017-01-30 22:29 ` Russell King - ARM Linux
2017-01-31 10:30 ` Russell King - ARM Linux
2017-01-31 11:20 ` Russell King - ARM Linux
2017-02-01 0:31 ` Steve Longerbeam
2017-02-01 0:58 ` Russell King - ARM Linux
2017-01-31 15:51 ` Philipp Zabel
2017-01-31 16:48 ` Philipp Zabel
2017-02-01 1:40 ` Steve Longerbeam
2017-02-07 16:18 ` [PATCH] media: imx: csi: fix crop rectangle reset in sink set_fmt Philipp Zabel
2017-01-07 2:11 ` [PATCH v3 18/24] media: imx: Add SMFC subdev driver Steve Longerbeam
2017-02-01 18:39 ` Russell King - ARM Linux
2017-02-01 18:52 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 19/24] media: imx: Add IC subdev drivers Steve Longerbeam
2017-01-20 14:29 ` Hans Verkuil
2017-01-25 2:39 ` Steve Longerbeam
2017-01-30 22:29 ` Russell King - ARM Linux
2017-01-07 2:11 ` [PATCH v3 20/24] media: imx: Add Camera Interface subdev driver Steve Longerbeam
2017-01-20 14:38 ` Hans Verkuil
2017-01-24 2:15 ` Steve Longerbeam
2017-01-31 13:42 ` Russell King - ARM Linux
2017-01-31 18:21 ` Steve Longerbeam
2017-01-31 20:33 ` Russell King - ARM Linux
2017-01-31 21:55 ` Ian Arkver
2017-01-31 22:04 ` Russell King - ARM Linux
2017-01-31 22:33 ` Ian Arkver
2017-01-31 22:36 ` Steve Longerbeam
2017-01-31 23:30 ` Russell King - ARM Linux
2017-01-31 23:41 ` Steve Longerbeam
2017-02-02 22:35 ` Russell King - ARM Linux
2017-02-07 1:52 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 21/24] media: imx: Add MIPI CSI-2 Receiver " Steve Longerbeam
2017-01-30 22:30 ` Russell King - ARM Linux
2017-01-31 0:01 ` Russell King - ARM Linux
2017-01-31 9:49 ` Philipp Zabel
2017-02-01 1:02 ` Steve Longerbeam
2017-02-01 1:13 ` Russell King - ARM Linux
2017-01-31 0:31 ` Russell King - ARM Linux
2017-01-31 2:11 ` Steve Longerbeam
2017-02-01 23:44 ` Russell King - ARM Linux
2017-02-02 0:04 ` Steve Longerbeam
2017-02-02 11:50 ` Philipp Zabel
2017-02-08 23:23 ` Steve Longerbeam
2017-02-08 23:42 ` Russell King - ARM Linux
2017-02-09 23:49 ` Steve Longerbeam
2017-02-09 23:51 ` Steve Longerbeam
2017-02-13 9:20 ` Philipp Zabel
2017-02-13 23:20 ` Steve Longerbeam
2017-02-14 16:59 ` Philipp Zabel
2017-02-09 9:43 ` Philipp Zabel
2017-01-07 2:11 ` [PATCH v3 22/24] media: imx: Add MIPI CSI-2 OV5640 sensor " Steve Longerbeam
2017-01-20 14:48 ` Hans Verkuil
2017-01-25 19:10 ` Steve Longerbeam
2017-01-30 23:29 ` Russell King - ARM Linux
2017-01-31 3:31 ` Steve Longerbeam
2017-02-02 10:36 ` Laurent Pinchart
2017-02-12 22:53 ` Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 23/24] media: imx: Add Parallel OV5642 " Steve Longerbeam
2017-01-07 2:11 ` [PATCH v3 24/24] ARM: imx_v6_v7_defconfig: Enable staging video4linux drivers Steve Longerbeam
2017-01-11 23:14 ` [PATCH v3 00/24] i.MX Media Driver Tim Harvey
2017-01-12 3:22 ` Steve Longerbeam
2017-01-12 21:13 ` Tim Harvey
2017-01-12 22:32 ` Steve Longerbeam
2017-01-13 21:04 ` Tim Harvey
2017-01-20 13:52 ` Hans Verkuil
2017-01-20 16:31 ` Philipp Zabel
2017-01-20 18:40 ` Steve Longerbeam
2017-01-20 20:39 ` Hans Verkuil
2017-01-23 11:00 ` Philipp Zabel
2017-01-23 11:08 ` Hans Verkuil
2017-01-24 11:28 ` Philipp Zabel
2017-01-23 23:08 ` Steve Longerbeam
2017-01-24 11:27 ` Philipp Zabel
2017-01-28 19:27 ` Steve Longerbeam
2017-01-30 13:06 ` Russell King - ARM Linux
2017-01-31 10:09 ` Philipp Zabel
2017-01-31 13:14 ` Russell King - ARM Linux
2017-01-31 13:35 ` Philipp Zabel
2017-01-31 14:04 ` Russell King - ARM Linux
2017-01-31 0:45 ` Russell King - ARM Linux
2017-01-31 1:06 ` Russell King - ARM Linux
2017-01-31 2:06 ` Steve Longerbeam
2017-01-31 1:22 ` Steve Longerbeam
2017-01-31 9:49 ` Philipp Zabel
2017-01-31 10:21 ` Russell King - ARM Linux
2017-01-31 11:00 ` Russell King - ARM Linux
2017-01-31 23:43 ` Steve Longerbeam
2017-02-01 0:23 ` Russell King - ARM Linux
2017-02-01 1:54 ` Steve Longerbeam
2017-02-01 9:20 ` Russell King - ARM Linux
2017-01-31 13:54 ` Philipp Zabel
2017-01-31 14:25 ` Philipp Zabel
2017-01-31 15:03 ` Russell King - ARM Linux
2017-02-01 1:26 ` Steve Longerbeam
2017-02-01 9:30 ` Philipp Zabel
2017-02-01 10:11 ` Russell King - ARM Linux
2017-02-01 10:42 ` Philipp Zabel
2017-02-01 10:53 ` Russell King - ARM Linux
2017-02-02 0:19 ` Steve Longerbeam
2017-02-03 14:41 ` Laurent Pinchart
2017-02-03 17:56 ` Steve Longerbeam
2017-02-15 2:27 ` Steve Longerbeam
2017-02-15 9:33 ` Philipp Zabel
2017-02-02 17:22 ` Russell King - ARM Linux
2017-02-02 17:31 ` Steve Longerbeam
2017-02-02 17:56 ` Russell King - ARM Linux
2017-02-02 18:26 ` Steve Longerbeam
2017-02-02 18:58 ` Russell King - ARM Linux
2017-02-02 19:12 ` Steve Longerbeam
2017-02-02 22:29 ` Russell King - ARM Linux
2017-02-03 18:49 ` Steve Longerbeam
2017-02-03 14:21 ` Laurent Pinchart [this message]
2017-02-03 14:31 ` vb2 queue_setup documentation clarification (was "Re: [PATCH v3 00/24] i.MX Media Driver") Hans Verkuil
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