From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bh-25.webhostbox.net ([208.91.199.152]:59497 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755288AbbLBCOc (ORCPT ); Tue, 1 Dec 2015 21:14:32 -0500 Date: Tue, 1 Dec 2015 18:14:29 -0800 From: Guenter Roeck To: Marc Titinger Cc: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] iio: ina2xx: add support for TI INA2xx Power Monitors Message-ID: <20151202021429.GA19098@roeck-us.net> References: <1448884155-2546-1-git-send-email-mtitinger@baylibre.com> <1448884155-2546-2-git-send-email-mtitinger@baylibre.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1448884155-2546-2-git-send-email-mtitinger@baylibre.com> Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On Mon, Nov 30, 2015 at 12:49:14PM +0100, Marc Titinger wrote: > in SOFTWARE buffer mode, a kthread will capture the active scan_elements > into a kfifo, then compute the remaining time until the next capture tick > and do an active wait (udelay). > > This will produce a stream of up to fours channels plus a 64bits > timestamps (ns). > > Tested with ina226, on BeagleBoneBlack. > > Datasheet: http://www.ti.com/lit/gpn/ina226 > > Signed-off-by: Marc Titinger > --- > drivers/iio/adc/Kconfig | 9 + > drivers/iio/adc/Makefile | 1 + > drivers/iio/adc/ina2xx-iio.c | 678 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 688 insertions(+) > create mode 100644 drivers/iio/adc/ina2xx-iio.c > + [ ... ] > + > +static const struct i2c_device_id ina2xx_id[] = { > + {"ina219", ina219}, > + {"ina220", ina219}, > + {"ina226", ina226}, > + {"ina230", ina226}, > + {"ina231", ina226}, > + {} > +}; I wonder what is going to happen if both this driver and the hwmon driver for the same chips are configured in a system which supports devicetree (or any system, really). Unless I am missing something, the result will be that both drivers will try to instantiate, and one will fail with -EBUSY. Or the instantiated driver is more or less random, depending on which one happens to be loaded. Not a good situation to be in. For the time being, it might make sense to add cross-dependencies in Kconfig to only permit one of the two drivers to be configured. Ultimately we may need a better solution for the iio-hwmon bridge, one that makes the underlying driver transparent in both devicetree properties and user space ABI. No idea how to do that, though. Guenter