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From: Wolfram Sang <wsa@the-dreams.de>
To: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Alexandre Courbot <gnurou@gmail.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Vignesh R <vigneshr@ti.com>, Yong Li <yong.b.li@intel.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Peter Rosin <peda@axentia.se>,
	linux-i2c <linux-i2c@vger.kernel.org>,
	linux-gpio <linux-gpio@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 0/4] gpio: fix an incorrect lockdep warning
Date: Sat, 24 Sep 2016 10:56:04 +0200	[thread overview]
Message-ID: <20160924085604.GC1434@katana> (raw)
In-Reply-To: <1474041765-17818-1-git-send-email-bgolaszewski@baylibre.com>

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On Fri, Sep 16, 2016 at 06:02:41PM +0200, Bartosz Golaszewski wrote:
> If an I2C GPIO multiplexer is driven by a GPIO provided by an expander
> when there's a second expander using the same device driver on one of
> the I2C bus segments, lockdep prints a deadlock warning when trying to
> set the direction or the value of the GPIOs provided by the second
> expander.
> 
> This series exports an already existing function from i2c-core as
> public API and reuses it in pca953x to pass a correct lock subclass
> to lockdep.
> 
> Note: if this series gets merged, I'll prepare follow-up patches for
> other expanders for which a similar problem could potentially occur.
> 
> Tested with the following setup:
> 
>  -------             ---------  Bus segment 1 |         |
> |       |           |         |---------------  Devices
> |       | SCL/SDA   |         |               |         |
> | Linux |-----------| I2C MUX |                - - - - -
> |       |    |      |         | Bus segment 2
> |       |    |      |         |-------------------
>  -------     |       ---------                    |
>              |           |                    - - - - -
>         ------------     | MUX GPIO          |         |
>        |            |    |                     Devices
>        |    GPIO    |    |                   |         |
>        | Expander 1 |----                     - - - - -
>        |            |                             |
>         ------------                              | SCL/SDA
>                                                   |
>                                              ------------
>                                             |            |
>                                             |    GPIO    |
>                                             | Expander 2 |
>                                             |            |
>                                              ------------
> 
> where expander 1 is a pca9534 and expander 2 is a pca9535.
> 
> v1 -> v2:
> - added patches 1/4, 2/4 & 3/4
> - used i2c_adapter_depth() in patch 4/4 in order to detect multiple
>   adapter nesting
> 
> Bartosz Golaszewski (4):
>   i2c: export i2c_adapter_depth()
>   lockdep: make MAX_LOCKDEP_SUBCLASSES unconditionally visible
>   i2c: add a warning to i2c_adapter_depth()
>   gpio: pca953x: fix an incorrect lockdep warning

Applied to for-next, thanks!


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      parent reply	other threads:[~2016-09-24  8:56 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-16 16:02 [PATCH v2 0/4] gpio: fix an incorrect lockdep warning Bartosz Golaszewski
2016-09-16 16:02 ` [PATCH v2 1/4] i2c: export i2c_adapter_depth() Bartosz Golaszewski
2016-09-16 16:02 ` [PATCH v2 2/4] lockdep: make MAX_LOCKDEP_SUBCLASSES unconditionally visible Bartosz Golaszewski
2016-09-16 16:02 ` [PATCH v2 3/4] i2c: add a warning to i2c_adapter_depth() Bartosz Golaszewski
2016-09-16 16:02 ` [PATCH v2 4/4] gpio: pca953x: fix an incorrect lockdep warning Bartosz Golaszewski
2016-09-21  5:45   ` Wolfram Sang
2016-09-23  8:10     ` Linus Walleij
2016-09-24  8:55       ` Wolfram Sang
2016-09-24  9:15   ` Wolfram Sang
2016-09-24 14:26     ` Geert Uytterhoeven
2016-09-16 17:26 ` [PATCH v2 0/4] gpio: " Wolfram Sang
2016-09-16 17:45   ` Peter Rosin
2016-09-16 17:58     ` Wolfram Sang
2016-09-18  8:52       ` Peter Rosin
2016-09-18 19:43         ` Bartosz Golaszewski
2016-09-18 19:45           ` Bartosz Golaszewski
2016-09-19  8:01             ` Peter Rosin
2016-09-19  8:14               ` Peter Zijlstra
2016-09-19  8:48                 ` Peter Rosin
2016-09-19  9:03                   ` Peter Zijlstra
2016-09-20  8:48                     ` Peter Rosin
2016-09-20 10:07                       ` Bartosz Golaszewski
2016-09-20 10:28                         ` Peter Zijlstra
2016-09-20 10:48                         ` Peter Rosin
2016-09-20 11:30                           ` Geert Uytterhoeven
2016-09-20 12:32                             ` Bartosz Golaszewski
2016-09-20 15:33                       ` Thomas Gleixner
2016-09-21  9:47                         ` Peter Rosin
2016-09-17  1:19 ` Peter Zijlstra
2016-09-17 10:18   ` Wolfram Sang
2016-09-17 18:59     ` Bartosz Golaszewski
2016-09-24  8:56 ` Wolfram Sang [this message]

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