From: Stefan Agner <stefan@agner.ch>
To: Greg KH <greg@kroah.com>
Cc: stable@vger.kernel.org, Wolfram Sang <wsa@the-dreams.de>,
stable@kernel.org
Subject: Re: [PATCH] i2c: imx: defer probe if bus recovery GPIOs are not ready
Date: Wed, 09 Nov 2016 10:45:54 -0800 [thread overview]
Message-ID: <1b2f6a1ec654d79375d62f7d8fb590bd@agner.ch> (raw)
In-Reply-To: <20161109061145.GB2739@kroah.com>
On 2016-11-08 22:11, Greg KH wrote:
> On Tue, Nov 08, 2016 at 04:34:50PM -0800, Stefan Agner wrote:
>> On 2016-11-08 16:32, Stefan Agner wrote:
>> > commit 533169d164c6b4c8571d0d48779f6ff6be593d72 upstream.
>> >
>> > Some SoC might load the GPIO driver after the I2C driver and
>> > using the I2C bus recovery mechanism via GPIOs. In this case
>> > it is crucial to defer probing if the GPIO request functions
>> > do so, otherwise the I2C driver gets loaded without recovery
>> > mechanisms enabled.
>> >
>> > Signed-off-by: Stefan Agner <stefan@agner.ch>
>> > Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
>> > Acked-by: Li Yang <leoyang.li@nxp.com>
>> > Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
>> > Cc: stable@kernel.org
>>
>> I forgot to mention, this should be applied to 4.4 only.
>
> Did you build the code there?
Oh, I built it on a branch where I had some other patches applied, sorry
about that.
>
>> Later versions made the return value void, and it would require a larger
>> rework. I am mainly concerned about LTS...
>
> I don't see this working for either 4.4 or 4.8-stable right now, do you?
No, the patch really doesn't work for 4.4 through 4.8. The patch relies
on commit fd8961c5ba9e6c ("i2c: imx: make bus recovery through pinctrl
optional"), which is not marked for stable (and probably also not
suitable actually).
The issue can only be observed on Vybrid SoC's with I2C bus recovery
enabled. The upstream device trees don't use I2C bus recovery so far. So
the patch is actually just enabling a feature we did not have so far...
Given all this circumstances, I think we should not further waste our
time and try to backport this patch for stable.
Sorry for the noise.
--
Stefan
next prev parent reply other threads:[~2016-11-09 18:52 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-09 0:32 [PATCH] i2c: imx: defer probe if bus recovery GPIOs are not ready Stefan Agner
2016-11-09 0:34 ` Stefan Agner
2016-11-09 6:11 ` Greg KH
2016-11-09 18:45 ` Stefan Agner [this message]
2016-11-09 6:10 ` Greg KH
-- strict thread matches above, loose matches on Subject: below --
2016-09-27 0:18 Stefan Agner
2016-09-27 6:44 ` Uwe Kleine-König
2016-09-27 18:31 ` Leo Li
2016-10-25 10:16 ` Wolfram Sang
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