From: Jean Delvare <khali@linux-fr.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>, Chris Wolfe <cwolfe@chromium.org>
Cc: Alan Cox <alan@linux.intel.com>,
Nathan Royer <nroyer@invensense.com>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@suse.de>,
Jonathan Cameron <jic23@cam.ac.uk>, Jiri Kosina <jkosina@suse.cz>,
linux-kernel@vger.kernel.org, linux-input@vger.kernel.org
Subject: Re: [PATCH 11/11] misc: Add slave driver for bma085 pressure sensor
Date: Fri, 1 Jul 2011 18:09:03 +0200 [thread overview]
Message-ID: <20110701180903.0fa2cbc9@endymion.delvare> (raw)
In-Reply-To: <20110701154150.0ac303a3@lxorguk.ukuu.org.uk>
On Fri, 1 Jul 2011 15:41:50 +0100, Alan Cox wrote:
> > Just to field this quickly, since I've been playing with the hardware
>
> (Ditto)
>
> > Part of the reason I got started on the KXTF9 driver was to try and
> > understand how a normal kernel driver could cope with the "here and
> > gone again" behavior of being on the MPU's secondary bus.
>
> It's a hot pluggable bus - no different to an i2c bus on a hot pluggable
> device.
>
> I would guess however that if you knew the device was going to be used for
> the mpu3050 only you'd not add the "slave" devices in your platform data
> in the first place as well so they didn't bounce in and out and you'd
> probably teach the mpu3050 code to not create the bus if it was then
> going to destroy it again a moment later.
I didn't look in the code in details, but I see no reason to destroy
buses. This is a standard multi-master case, where a given I2C bus
segment can be driven by two masters. If both the host I2C controller
and the MPU3050 master are fully I2C compliant, it should be no problem
to let both coexist. If you really need to handle mutual exclusion
(e.g. the MPU3050 implementation forces you to do so), you can leverage
the i2c multiplexing support for this, which is available since kernel
2.6.36. See drivers/i2c/muxes/pca9541.c for an example implementation.
--
Jean Delvare
next prev parent reply other threads:[~2011-07-01 16:09 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-01 2:18 [PATCH 01/11] misc: inv_mpu primary header file and README file Nathan Royer
2011-07-01 2:18 ` [PATCH 02/11] misc: mpu3050 Register definition and Private data Nathan Royer
2011-07-01 2:18 ` [PATCH 03/11] misc: mpu3050 /dev/mpu implementation Nathan Royer
2011-07-01 2:18 ` [PATCH 04/11] misc: IRQ handling for MPU3050 and slave devices Nathan Royer
2011-07-01 2:18 ` [PATCH 05/11] misc: MPU3050 and slave device configuration Nathan Royer
2011-07-01 17:55 ` Nathan Royer
2011-07-01 2:18 ` [PATCH 06/11] misc: inv_mpu logging and debugging support Nathan Royer
2011-07-01 2:18 ` [PATCH 07/11] misc: I2C communication with the MPU3050 and slave devices Nathan Royer
2011-07-01 2:18 ` [PATCH 08/11] misc: Kconfig and Makefile changes for inv_mpu driver Nathan Royer
2011-07-01 17:10 ` Randy Dunlap
2011-07-01 2:18 ` [PATCH 09/11] misc: Add slave driver for kxtf9 accelerometer Nathan Royer
2011-07-01 2:18 ` [PATCH 10/11] misc: Add slave driver for ak8975 compass driver Nathan Royer
2011-07-01 2:18 ` [PATCH 11/11] misc: Add slave driver for bma085 pressure sensor Nathan Royer
2011-07-01 7:56 ` Alan Cox
2011-07-01 8:47 ` Jean Delvare
2011-07-01 14:28 ` Chris Wolfe
2011-07-01 14:41 ` Alan Cox
2011-07-01 15:52 ` Chris Wolfe
2011-07-01 17:00 ` Alan Cox
2011-07-01 17:56 ` Nathan Royer
2011-07-01 16:09 ` Jean Delvare [this message]
2011-07-01 9:05 ` Jonathan Cameron
2011-07-01 10:35 ` Manuel Stahl
2011-07-01 3:09 ` [PATCH 01/11] misc: inv_mpu primary header file and README file Greg KH
2011-07-01 7:29 ` Alan Cox
2011-07-01 9:00 ` Jonathan Cameron
2011-07-01 3:59 ` Chris Wolfe
2011-07-05 18:08 ` Nathan Royer
2011-07-01 7:53 ` Alan Cox
2011-07-01 9:08 ` Jonathan Cameron
2011-07-01 16:39 ` Nathan Royer
2011-07-03 11:29 ` Jonathan Cameron
2011-07-04 8:16 ` Alan Cox
2011-07-06 1:49 ` Nathan Royer
2011-07-06 9:07 ` Jonathan Cameron
2011-07-06 20:25 ` Nathan Royer
2011-07-06 10:54 ` Alan Cox
2011-07-06 21:27 ` Nathan Royer
2011-07-07 7:40 ` Alan Cox
2011-07-08 1:25 ` Nathan Royer
2011-07-08 11:21 ` Jonathan Cameron
2011-07-08 16:24 ` Nathan Royer
2011-07-04 20:06 ` Eric Andersson
2011-07-01 21:04 ` Arnd Bergmann
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