From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: <linux-i2c@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-omap@vger.kernel.org>
Subject: Re: [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices"
Date: Fri, 7 Jun 2013 13:10:38 +0300 [thread overview]
Message-ID: <51B1B19E.1050200@ti.com> (raw)
In-Reply-To: <20130607090623.GC3428@katana>
Hi Wolfram,
On 06/07/2013 12:06 PM, Wolfram Sang wrote:
>> 3) Thinking about Mainline: To reach the same target - no I2C
>> detection - and taking
>> into account above assumption "No changes in default behavior"
>> the following will need to be done:
>> - change i2c-omap/i2c-gpio DT bindings and add parameter which will
>> allow to change
>> .class value for adapter. Not sure, it's possible because this parameter
>> will be Linux and not HW specific (smth. like "i2c_disable_detection")
>> - update drivers i2c-omap/i2c-gpio to use "i2c_disable_detection"
>> - update OMAP4/5 DTS files
>>
>> So, It seemed a good solution for me to add 6 lines of code in i2c-core.c
>> instead of doing all that stuff.
> Well... I understand the "default behaviour" issue, yet I still think
> that setting class to 0 is the right thing to do. OMAP is an embedded
> SoC which always had i2c_board_info or devictree which are the preferred
> ways of instantiating. Given that, I would accept a patch setting it to
> 0. The more user friendly way might be to introduce a new class which
> makes users aware of the issue. Proof of concept follows, only compile
> tested.
>
That sounds good to me - I can prepare patch for i2c-omap.c.
But, there is still an open question regarding *i2c-gpio.c* which,
actually, a source of biggest part of delay.
Potentially, it can be tunned using "timeout" value. But, again, this
is additional work/patches to workaround unneeded system feature:
- "timeout" should not break interaction with I2C devices on i2c-gpio
bus and, at same time, speed up boot;
- DTS/board files need to be updated.
May be, just may be), we can continue with
CONFIG_I2C_DISABLE_DEVICE_DETECTION,
and print deprecation warning for each registered adapter
if this config option is defined.
- grygorii
next prev parent reply other threads:[~2013-06-07 10:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-04 17:33 [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices" Grygorii Strashko
2013-06-04 17:49 ` Wolfram Sang
2013-06-05 16:13 ` Grygorii Strashko
2013-06-07 9:06 ` Wolfram Sang
2013-06-07 9:09 ` [RFC] i2c: add deprecation warning for class based instantiation Wolfram Sang
2013-06-19 10:15 ` Wolfram Sang
2013-06-19 18:21 ` Grygorii Strashko
2013-06-20 18:37 ` Wolfram Sang
2013-06-19 18:22 ` Grygorii Strashko
2013-06-19 18:22 ` [RFC 1/2] i2c: omap: drop class based instantiation of slaves Grygorii Strashko
2013-06-19 18:22 ` [RFC 2/2] i2c: gpio: " Grygorii Strashko
2013-06-07 10:10 ` Grygorii Strashko [this message]
2013-06-07 21:28 ` [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices" Wolfram Sang
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