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From: Wolfram Sang <wsa@the-dreams.de>
To: Luca Ceresoli <luca@lucaceresoli.net>
Cc: Peter Rosin <peda@axentia.se>, jacopo mondi <jacopo@jmondi.org>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
	"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@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>,
	Vladimir Zapolskiy <vz@mleia.com>
Subject: Re: [RFC,v2 2/6] i2c: add I2C Address Translator (ATR) support
Date: Tue, 10 Sep 2019 19:46:53 +0100
Message-ID: <20190910184653.GB5581@kunai> (raw)
In-Reply-To: <2d770b36-9521-820d-726a-bc9b52048ef8@lucaceresoli.net>

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> I still have to examine in depth all of the problems in the i2c-mux
> documented in Documentation/i2c/i2c-topology (thanks for having written
> those docs!), but at first sight it looks like the ATR is not going to
> introduce big problems because of how it works.

Assuming we are using the previously discussed NEEDS_ATR flag for the adapter
instead of the attach/detach callbacks:

Can't we then simply understand an ATR as a generic 1:1 mapping device
which can be setup when registering an adapter?

When we add an adapter using i2c_add_adapter, we have:


              .-----.  Slave X @ 0x10
  .-----.     |     |   |
  | CPU |--A--| ATR |---+---- B
  `-----'     |     |
              `-----'

When we use i2c_add_mux_adapter, we have:


                                Slave X @ 0x10
              .-----.   .-----.   |
  .-----.     |     |---| ATR |---+---- B
  | CPU |--A--| MUX |   '-----'
  `-----'     |     |   .-----.
              |     |---| ATR |---+---- C
              `-----'   '-----'   |
                                 Slave Y @ 0x10


That way we could keep the topology handling solely to the mux-core.

Am I overlooking something?


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  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 [this message]
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
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

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