Linux-Renesas-SoC Archive on lore.kernel.org
 help / color / Atom feed
From: Jacopo Mondi <jacopo@jmondi.org>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: "Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
	"Benoit Parrot" <bparrot@ti.com>,
	linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	"Michal Simek" <michal.simek@xilinx.com>
Subject: Re: [PATCH v2 16/30] v4l: subdev: Add [GS]_ROUTING subdev ioctls and operations
Date: Fri, 22 Feb 2019 09:46:34 +0100
Message-ID: <20190222084634.26clkuumd3mgsw4f@uno.localdomain> (raw)
In-Reply-To: <20190221234936.pbbymgzmqrv7ypje@kekkonen.localdomain>

[-- Attachment #1: Type: text/plain, Size: 6363 bytes --]

Hi Sakari,

On Fri, Feb 22, 2019 at 01:49:36AM +0200, Sakari Ailus wrote:
> Hi Jacopo,
>
> On Thu, Feb 21, 2019 at 03:59:20PM +0100, Jacopo Mondi wrote:
> > Hi Sakari, Laurent, Niklas,
> >    (another) quick question, but a different one :)
> >
> > On Wed, Jan 16, 2019 at 01:51:45AM +0200, Laurent Pinchart wrote:
> > > Hi Niklas,
> > >
> > > Thank you for the patch.
> > >
> > > On Fri, Nov 02, 2018 at 12:31:30AM +0100, Niklas Söderlund wrote:
> > > > From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > >
> > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> > > >
> > > > - Add sink and source streams for multiplexed links
> > > > - Copy the argument back in case of an error. This is needed to let the
> > > >   caller know the number of routes.
> > > >
> > > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > > > Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> > > > ---
> > > >  drivers/media/v4l2-core/v4l2-ioctl.c  | 20 +++++++++++++-
> > > >  drivers/media/v4l2-core/v4l2-subdev.c | 28 +++++++++++++++++++
> > > >  include/media/v4l2-subdev.h           |  7 +++++
> > > >  include/uapi/linux/v4l2-subdev.h      | 40 +++++++++++++++++++++++++++
> > >
> > > Missing documentation :-(
> > >
> > > >  4 files changed, 94 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > > index 7de041bae84fb2f2..40406acb51ec0906 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > > @@ -19,6 +19,7 @@
> > > >  #include <linux/kernel.h>
> > > >  #include <linux/version.h>
> > > >
> > > > +#include <linux/v4l2-subdev.h>
> > > >  #include <linux/videodev2.h>
> > > >
> > > >  #include <media/v4l2-common.h>
> > > > @@ -2924,6 +2925,23 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size,
> > > >  		}
> > > >  		break;
> > > >  	}
> > > > +
> > > > +	case VIDIOC_SUBDEV_G_ROUTING:
> > > > +	case VIDIOC_SUBDEV_S_ROUTING: {
> > > > +		struct v4l2_subdev_routing *route = parg;
> > > > +
> > > > +		if (route->num_routes > 0) {
> > > > +			if (route->num_routes > 256)
> > > > +				return -EINVAL;
> > > > +
> > > > +			*user_ptr = (void __user *)route->routes;
> > > > +			*kernel_ptr = (void *)&route->routes;
> > > > +			*array_size = sizeof(struct v4l2_subdev_route)
> > > > +				    * route->num_routes;
> > > > +			ret = 1;
> > > > +		}
> > > > +		break;
> > > > +	}
> > > >  	}
> > > >
> > > >  	return ret;
> > > > @@ -3033,7 +3051,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
> > > >  	 * Some ioctls can return an error, but still have valid
> > > >  	 * results that must be returned.
> > > >  	 */
> > > > -	if (err < 0 && !always_copy)
> > > > +	if (err < 0 && !always_copy && cmd != VIDIOC_SUBDEV_G_ROUTING)
> > >
> > > This seems like a hack. Shouldn't VIDIOC_SUBDEV_G_ROUTING set
> > > always_copy instead ?
> > >
> > > >  		goto out;
> > > >
> > > >  out_array_args:
> > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > > > index 792f41dffe2329b9..1d3b37cf548fa533 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > > > @@ -516,7 +516,35 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
> > > >
> > > >  	case VIDIOC_SUBDEV_QUERYSTD:
> > > >  		return v4l2_subdev_call(sd, video, querystd, arg);
> > > > +
> > > > +	case VIDIOC_SUBDEV_G_ROUTING:
> > > > +		return v4l2_subdev_call(sd, pad, get_routing, arg);
> > > > +
> > > > +	case VIDIOC_SUBDEV_S_ROUTING: {
> > > > +		struct v4l2_subdev_routing *route = arg;
> > > > +		unsigned int i;
> > > > +
> > > > +		if (route->num_routes > sd->entity.num_pads)
> > > > +			return -EINVAL;
> > > > +
> > > > +		for (i = 0; i < route->num_routes; ++i) {
> >
> > How have you envisioned the number of routes to be negotiated with
> > applications? I'm writing the documentation for this ioctl, and I
> > would like to insert this part as well.
> >
> > Would a model like the one implemented in G_TOPOLOGY work in your
> > opinion? In my understanding, at the moment applications do not have a
> > way to reserve a known number of routes entries, but would likely
> > reserve 'enough(tm)' (ie 256) and pass them to the G_ROUTING ioctl that the
> > first time will likely adjust the number of num_routes and return -ENOSPC.
> >
> > Wouldn't it work to make the IOCTL behave in a way that it
> > expects the first call to be performed with (num_routes == 0) and no routes
> > entries reserved, and just adjust 'num_routes' in that case?
> > So that applications should call G_ROUTING a first time with
> > num_routes = 0, get back the number of routes entries, reserve memory
> > for them, and then call G_ROUTING again to have the entries populated
> > by the driver. Do you have different ideas or was this the intended
> > behavior already?
>
> I think whenever the number of routes isn't enough to return them all, the
> IOCTL should return -ENOSPC, and set the actual number of routes there. Not
> just zero. The user could e.g. try with a static allocation of some, and
> allocate memory if the static allocation turns not to be enough.

I see. That's fine, I just wanted to make sure I was not missing
something... Fine with me if num_routes is not adequate, it should be
corrected by the driver and -ENOSPC returned. How applications deal
with allocation is up to them (even if documentation might suggest to
perform and "call with 0, allocate, call again" sequence as a way to
ease this)

>
> Btw. the idea behind S_ROUTING behaviour was to allow multiple users to
> work on a single sub-device without having to know about each other. That's
> why there are flags to tell which routes are enabled and which are not.
>
> I'll be better available tomorrow, let's discuss e.g. on #v4l then.
>

Unfortunately I won't too much today :) I'll keep pinging in the next
days then, sorry about this :p

Thanks
   j

> --
> Sakari Ailus
> sakari.ailus@linux.intel.com

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

  reply index

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-01 23:31 [PATCH v2 00/30] v4l: add support for multiplexed streams Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 01/30] media: entity: Use pad as a starting point for graph walk Niklas Söderlund
2019-01-15 21:43   ` Laurent Pinchart
2018-11-01 23:31 ` [PATCH v2 02/30] media: entity: Use pads instead of entities in the media graph walk stack Niklas Söderlund
2019-01-15 22:03   ` Laurent Pinchart
2019-01-15 22:13     ` Sakari Ailus
2019-01-15 22:07   ` Laurent Pinchart
2018-11-01 23:31 ` [PATCH v2 03/30] media: entity: Walk the graph based on pads Niklas Söderlund
2019-01-15 22:21   ` Laurent Pinchart
     [not found]     ` <20190115223406.mxgzl36cp54gb7nv@kekkonen.localdomain>
2019-01-15 23:28       ` Laurent Pinchart
2019-01-22 14:50         ` Sakari Ailus
2019-02-14 15:15   ` Jacopo Mondi
2018-11-01 23:31 ` [PATCH v2 04/30] v4l: mc: Start walk from a specific pad in use count calculation Niklas Söderlund
2019-01-15 22:24   ` Laurent Pinchart
2019-01-15 22:36     ` Sakari Ailus
2018-11-01 23:31 ` [PATCH v2 05/30] media: entity: Move the pipeline from entity to pads Niklas Söderlund
2019-01-15 22:38   ` Laurent Pinchart
2019-01-15 22:48     ` Sakari Ailus
2019-02-14 15:53   ` Jacopo Mondi
2018-11-01 23:31 ` [PATCH v2 06/30] media: entity: Use pad as the starting point for a pipeline Niklas Söderlund
2019-01-15 22:54   ` Laurent Pinchart
2019-01-22 15:31     ` Sakari Ailus
2019-01-22 15:37       ` Laurent Pinchart
2019-01-22 16:16         ` Sakari Ailus
2018-11-01 23:31 ` [PATCH v2 07/30] media: entity: Add has_route entity operation Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 08/30] media: entity: Add media_has_route() function Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 09/30] media: entity: Swap pads if route is checked from source to sink Niklas Söderlund
2019-01-15 22:57   ` Laurent Pinchart
2019-01-22 15:15     ` Sakari Ailus
2019-01-22 15:20       ` Laurent Pinchart
2019-02-18  9:21         ` Jacopo Mondi
2019-02-22 12:18           ` Laurent Pinchart
2019-03-04 12:35             ` Jacopo Mondi
2019-03-05 20:04               ` Laurent Pinchart
2019-03-06  8:29                 ` Jacopo Mondi
2018-11-01 23:31 ` [PATCH v2 10/30] media: entity: Use routing information during graph traversal Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 11/30] media: entity: Skip link validation for pads to which there is no route to Niklas Söderlund
2019-01-15 23:13   ` Laurent Pinchart
2018-11-01 23:31 ` [PATCH v2 12/30] media: entity: Add an iterator helper for connected pads Niklas Söderlund
2019-01-15 23:24   ` Laurent Pinchart
2019-01-22 15:36     ` Sakari Ailus
2019-01-22 15:38       ` Laurent Pinchart
2019-01-22 16:21         ` Sakari Ailus
2018-11-01 23:31 ` [PATCH v2 13/30] media: entity: Add only connected pads to the pipeline Niklas Söderlund
2019-01-15 23:33   ` Laurent Pinchart
2018-11-01 23:31 ` [PATCH v2 14/30] media: entity: Add debug information in graph walk route check Niklas Söderlund
2019-01-15 23:35   ` Laurent Pinchart
2019-01-22 15:38     ` Sakari Ailus
2018-11-01 23:31 ` [PATCH v2 15/30] media: entity: Look for indirect routes Niklas Söderlund
2019-01-15 23:41   ` Laurent Pinchart
2019-01-22 15:56     ` Sakari Ailus
2018-11-01 23:31 ` [PATCH v2 16/30] v4l: subdev: Add [GS]_ROUTING subdev ioctls and operations Niklas Söderlund
2019-01-15 23:51   ` Laurent Pinchart
2019-01-22 16:14     ` Sakari Ailus
2019-01-22 17:00       ` Laurent Pinchart
2019-02-21 14:59     ` Jacopo Mondi
2019-02-21 23:49       ` Sakari Ailus
2019-02-22  8:46         ` Jacopo Mondi [this message]
2019-02-21 14:39   ` Jacopo Mondi
2019-02-21 22:31     ` Sakari Ailus
2019-02-22  8:40       ` Jacopo Mondi
2019-02-22 11:04         ` Sakari Ailus
2019-02-22 11:17           ` Jacopo Mondi
2019-02-22 11:29             ` Sakari Ailus
2019-02-22 13:37               ` Ian Arkver
2019-02-22 13:50               ` Geert Uytterhoeven
2018-11-01 23:31 ` [PATCH v2 17/30] v4l: subdev: compat: Implement handling for VIDIOC_SUBDEV_[GS]_ROUTING Niklas Söderlund
2019-01-08 10:04   ` Geert Uytterhoeven
2019-01-15 23:53   ` Laurent Pinchart
2019-01-22 15:57     ` Sakari Ailus
2019-02-18 11:21     ` Jacopo Mondi
2019-02-21 23:50       ` Sakari Ailus
2018-11-01 23:31 ` [PATCH v2 18/30] v4l: subdev: Take routing information into account in link validation Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 19/30] v4l: subdev: Improve link format validation debug messages Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 20/30] v4l: mc: Add an S_ROUTING helper function for power state changes Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 21/30] v4l: Add bus type to frame descriptors Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 22/30] v4l: Add CSI-2 bus configuration " Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 23/30] v4l: Add stream to frame descriptor Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 24/30] adv748x: csi2: add translation from pixelcode to CSI-2 datatype Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 25/30] adv748x: csi2: only allow formats on sink pads Niklas Söderlund
2019-02-21 14:18   ` Jacopo Mondi
2018-11-01 23:31 ` [PATCH v2 26/30] adv748x: csi2: describe the multiplexed stream Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 27/30] adv748x: csi2: add internal routing configuration Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 28/30] adv748x: afe: add routing support Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 29/30] rcar-csi2: use frame description information to configure CSI-2 bus Niklas Söderlund
2018-11-01 23:31 ` [PATCH v2 30/30] rcar-csi2: expose the subdevice internal routing Niklas Söderlund
2018-11-14 13:10   ` Nikita Yushchenko
2018-11-14 19:45     ` Niklas Söderlund
2018-12-03 22:16 ` [PATCH v2 00/30] v4l: add support for multiplexed streams Sakari Ailus
2018-12-05 22:09   ` Niklas Söderlund

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190222084634.26clkuumd3mgsw4f@uno.localdomain \
    --to=jacopo@jmondi.org \
    --cc=bparrot@ti.com \
    --cc=laurent.pinchart@ideasonboard.com \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=michal.simek@xilinx.com \
    --cc=niklas.soderlund+renesas@ragnatech.se \
    --cc=sakari.ailus@linux.intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Renesas-SoC Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-renesas-soc/0 linux-renesas-soc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-renesas-soc linux-renesas-soc/ https://lore.kernel.org/linux-renesas-soc \
		linux-renesas-soc@vger.kernel.org linux-renesas-soc@archiver.kernel.org
	public-inbox-index linux-renesas-soc


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-renesas-soc


AGPL code for this site: git clone https://public-inbox.org/ public-inbox