Linux-Media Archive on lore.kernel.org
 help / color / Atom feed
From: Wolfram Sang <wsa@the-dreams.de>
To: Luca Ceresoli <luca@lucaceresoli.net>
Cc: linux-media@vger.kernel.org, linux-i2c@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Hans Verkuil <hverkuil-cisco@xs4all.nl>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Kieran Bingham <kieran.bingham@ideasonboard.com>,
	Jacopo Mondi <jacopo@jmondi.org>,
	Vladimir Zapolskiy <vz@mleia.com>, Peter Rosin <peda@axentia.se>
Subject: Re: [RFC,v2 2/6] i2c: add I2C Address Translator (ATR) support
Date: Mon, 2 Sep 2019 22:42:08 +0200
Message-ID: <20190902204208.GA7253@kunai> (raw)
In-Reply-To: <20190723203723.11730-3-luca@lucaceresoli.net>

[-- Attachment #1: Type: text/plain, Size: 1227 bytes --]

Hi Luca,

> + * Topology:
> + *
> + *                       Slave X @ 0x10
> + *               .-----.   |
> + *   .-----.     |     |---+---- B
> + *   | CPU |--A--| ATR |
> + *   `-----'     |     |---+---- C
> + *               `-----'   |
> + *                       Slave Y @ 0x10
> + *
> + * Alias table:
> + *
> + *   Client  Alias
> + *   -------------
> + *      X    0x20
> + *      Y    0x30

Great that you already provided docs for this driver!

One huge drawback for me is the attach/detach callbacks. One year ago, I
removed a similar callback from the I2C core ("[PATCH 0/2] i2c: remove
deprecated attach_adapter callback") because some drivers did a lot of
crazy things there. It took years to remove all that.

What I could imagine here: the adapter (B and C each in the picture
above) gets a flag like NEEDS_ATR before registering to the core. The
flag means all clients on that bus will have their address translated.
The core will figure out a free alias when a device is registered. We
can then have an ATR specific callback with the original and translated
address as arguments, so one can setup the HW as needed.

Do you think that would work? Jacopo, does that meet GMSL as well?

Regards,

   Wolfram

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

  parent reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-23 20:37 [RFC,v2 0/6] TI camera serdes and I2C address translation Luca Ceresoli
2019-07-23 20:37 ` [RFC,v2 1/6] i2c: core: let adapters be notified of client attach/detach Luca Ceresoli
2019-07-23 20:37 ` [RFC,v2 2/6] i2c: add I2C Address Translator (ATR) support Luca Ceresoli
2019-09-01 14:31   ` jacopo mondi
2019-09-03  7:31     ` Luca Ceresoli
2019-09-03  7:37       ` Wolfram Sang
2019-09-04  8:09       ` Peter Rosin
2019-09-08 19:40         ` Luca Ceresoli
2019-09-10 18:46           ` Wolfram Sang
2019-09-08 20:45     ` Vladimir Zapolskiy
2019-09-09  4:56       ` Vladimir Zapolskiy
2019-09-10 17:40         ` Luca Ceresoli
2019-09-09  7:22       ` Wolfram Sang
2019-09-09 15:10         ` Vladimir Zapolskiy
2019-09-09 17:48           ` Luca Ceresoli
2019-09-10 17:16             ` Wolfram Sang
2019-09-02 20:42   ` Wolfram Sang [this message]
2019-09-03  8:48     ` Luca Ceresoli
2019-09-03  9:06       ` Wolfram Sang
2019-07-23 20:37 ` [RFC,v2 3/6] media: dt-bindings: add DS90UB954-Q1 video deserializer Luca Ceresoli
2019-08-13 15:44   ` Rob Herring
2019-08-19 22:41     ` Luca Ceresoli
2019-08-20 15:44       ` Rob Herring
2019-08-21 21:50         ` Luca Ceresoli
2019-09-02 20:48   ` Wolfram Sang
2019-09-03  9:09     ` Luca Ceresoli
2019-09-03  9:34       ` Wolfram Sang
2019-09-03 11:03         ` Luca Ceresoli
2019-09-03 14:16           ` Wolfram Sang
2019-09-10  9:43   ` Sakari Ailus
2019-09-10 15:02     ` Luca Ceresoli
2019-07-23 20:37 ` [RFC,v2 4/6] media: dt-bindings: add DS90UB953-Q1 video serializer Luca Ceresoli
2019-07-23 20:37 ` [RFC,v2 5/6] media: ds90ub954: new driver for TI DS90UB954-Q1 video deserializer Luca Ceresoli
2019-07-23 20:37 ` [RFC,v2 6/6] media: ds90ub953: new driver for TI DS90UB953-Q1 video serializer Luca Ceresoli

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=20190902204208.GA7253@kunai \
    --to=wsa@the-dreams.de \
    --cc=devicetree@vger.kernel.org \
    --cc=hverkuil-cisco@xs4all.nl \
    --cc=jacopo@jmondi.org \
    --cc=kieran.bingham@ideasonboard.com \
    --cc=laurent.pinchart@ideasonboard.com \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=luca@lucaceresoli.net \
    --cc=mark.rutland@arm.com \
    --cc=mchehab@kernel.org \
    --cc=peda@axentia.se \
    --cc=robh+dt@kernel.org \
    --cc=sakari.ailus@linux.intel.com \
    --cc=vz@mleia.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-Media Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-media/0 linux-media/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-media linux-media/ https://lore.kernel.org/linux-media \
		linux-media@vger.kernel.org linux-media@archiver.kernel.org
	public-inbox-index linux-media

Example config snippet for mirrors

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


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