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From: Jacopo Mondi <jacopo@jmondi.org>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: "Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"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 12:17:47 +0100
Message-ID: <20190222111747.tlj2xdjhnjwrlqxx@uno.localdomain> (raw)
In-Reply-To: <20190222110429.ybmqdwba5rszntb7@paasikivi.fi.intel.com>

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Hi Sakari,
    thanks for your suggestions.

On Fri, Feb 22, 2019 at 01:04:29PM +0200, Sakari Ailus wrote:
> Hi Jacopo,

[snip]

> > On the previous example, I thought about GMSL-like devices, that can
> > output the video streams received from different remotes in a
> > separate virtual channel, at the same time.
> >
> > A possible routing table in that case would be like:
> >
> > Pads 0, 1, 2, 3 = SINKS
> > Pad 4 = SOURCE with 4 streams (1 for each VC)
> >
> > 0/0 -> 4/0
> > 0/0 -> 4/1
> > 0/0 -> 4/2
> > 0/0 -> 4/3
> > 1/0 -> 4/0
> > 1/0 -> 4/1
> > 1/0 -> 4/2
> > 1/0 -> 4/3
> > 2/0 -> 4/0
> > 2/0 -> 4/1
> > 2/0 -> 4/2
> > 2/0 -> 4/3
> > 3/0 -> 4/0
> > 3/0 -> 4/1
> > 3/0 -> 4/2
> > 3/0 -> 4/3
>
> If more than one pad can handle multiplexed streams, then you may end up in
> a situation like that. Indeed.
>

Please note that in this case there is only one pad that can handle
multiplexed stream. The size of the routing table is the
multiplication of the total number of pads by the product of all
streams per pad. In this case (4 * (1 * 1 * 1 * 4))

> >
> > With only one route per virtual channel active at a time.

[snip]

> >
> > Thanks, I had a look at the MEDIA_ ioctls yesterday, G_TOPOLOGY in
> > particular, which uses several pointers to arrays.
> >
> > Unfortunately, I didn't come up with anything better than using a
> > translation structure, from the IOCTL layer to the subdevice
> > operations layer:
> > https://paste.debian.net/hidden/b192969d/
> > (sharing a link for early comments, I can send v3 and you can comment
> > there directly if you prefer to :)
>
> Hmm. That is a downside indeed. It's still a lesser problem than the compat
> code in general --- which has been a source for bugs as well as nasty
> security problems over time.
>

Good!

> I think we need a naming scheme for such structs. How about just
> calling that struct e.g. v4l2_subdev_krouting instead? It's simple, easy to
> understand and it includes a suggestion which one is the kernel-only
> variant.
>

I kind of like that! thanks!

> You can btw. zero the struct memory by assigning { 0 } to it in
> declaration. memset() in general is much more trouble. In this case you
> could even do the assignments in delaration as well.
>

Thanks, noted. I have been lazy and copied memset from other places in
the ioctl handling code. I should check on your suggestions because I
remember one of the many 0-initialization statement was a GCC specific one,
don't remember which...

Initializing in-place would solve both issues :)

> There is a check that requires that one pad is a source and another is a
> sink; I think we could remove that check as well.

Correct, I'll handle that!

Thanks again
   j

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

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  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
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 [this message]
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

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