linux-kernel - Re: [PATCH v3] i2c: mux: remove duplicated i2c

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Date:   Wed, 10 Oct 2018 17:48:20 +0200
From:   Luca Ceresoli <lucaceresoli77@...il.com>
To:     Peter Rosin <peda@...ntia.se>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Luca Ceresoli <luca@...aceresoli.net>,
        Wolfram Sang <wsa@...-dreams.de>
Subject: Re: [PATCH v3] i2c: mux: remove duplicated i2c_algorithm

Hi Peter,

On 08/10/2018 23:43, Peter Rosin wrote:
> On 2018-10-03 17:19, Luca Ceresoli wrote:
>> From: Luca Ceresoli <luca@...aceresoli.net>
>>
>> i2c-mux instantiates one i2c_algorithm for each downstream adapter.
>> However these algorithms are all identical, depending only on the
>> parent adapter.
>>
>> Avoid duplication by hoisting the i2c_algorithm from the adapters to
>> the i2c_mux_core object, and reuse it in all the adapters.
> 
> Ouch, while I like the concept of having one i2c_algorithm per mux,
> this patch is not working. Various i2c-mux drivers set the
> muxc->mux_locked variable *after* the i2c_mux_alloc call, and this
> patch breaks such use.
> 
> So, the patch needs some reworking. Sorry for not noticing this
> earlier.

Thanks for the heads up.

3 drivers have the issue you mentioned, and two of them are not trivial
to fix. Ok, as soon as I can spend a little time on this I'll have a
look and hopefully send a fixed patch.

Regards,
-- 
Luca