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From: Luca Ceresoli <luca@lucaceresoli.net>
To: Wolfram Sang <wsa@the-dreams.de>
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: Tue, 3 Sep 2019 10:48:41 +0200
Message-ID: <8482d1e2-b1d9-3da5-5b1f-b7e492a87368@lucaceresoli.net> (raw)
In-Reply-To: <20190902204208.GA7253@kunai>

Hi Wolfram,

On 02/09/19 22:42, Wolfram Sang wrote:
> 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.

Oh dear, I was completely unaware, apologies! :-)

> 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 mean moving the alias selection code from i2c-atr.c to the i2c
core? And the rest of the ATR core too?

> Do you think that would work?

Yes.

-- 
Luca

  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
2019-09-03  8:48     ` Luca Ceresoli [this message]
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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