From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bh-25.webhostbox.net ([208.91.199.152]:36687 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751668AbbLBQop (ORCPT ); Wed, 2 Dec 2015 11:44:45 -0500 Subject: Re: [PATCH v2 1/2] iio: ina2xx: add support for TI INA2xx Power Monitors To: Marc Titinger References: <1448884155-2546-1-git-send-email-mtitinger@baylibre.com> <1448884155-2546-2-git-send-email-mtitinger@baylibre.com> <20151202021429.GA19098@roeck-us.net> <565EC5DB.5040401@baylibre.com> <565F169D.2050709@roeck-us.net> <565F1A44.3080504@baylibre.com> Cc: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org From: Guenter Roeck Message-ID: <565F1FF8.5030508@roeck-us.net> Date: Wed, 2 Dec 2015 08:44:40 -0800 MIME-Version: 1.0 In-Reply-To: <565F1A44.3080504@baylibre.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 12/02/2015 08:20 AM, Marc Titinger wrote: > On 02/12/2015 17:04, Guenter Roeck wrote: >> On 12/02/2015 02:20 AM, Marc Titinger wrote: >>> On 02/12/2015 03:14, Guenter Roeck wrote: >>>> 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. >>> >>> I agree, we should put a mutual exclusion in Kconfig, plus maybe a >>> cross-reference in the help section. >>> >>>> >>>> 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. >>>> >>> >>> IDK if ina2xx is a special case or if this matter of dual driver >>> stacks for the same chip already occurred and requires specific >>> plumbing. Making the user aware of the mutual of the exclusion sounds >>> fine with me. >>> >> htu21. We'll drop that driver from hwmon with the 4.5 kernel. >> We could just drop ina2xx as well, but it is more widely used >> and referenced from dts files. The ABI changes, so I am not sure >> if we can just do that. > > I changed iio/adc/Kconfig to the following: > > +config INA2XX_ADC > + tristate "Texas Instruments INA2xx Power Monitors IIO driver" > + depends on I2C && !SENSORS_INA2XX > + select REGMAP_I2C > + select IIO_BUFFER > + select IIO_KFIFO_BUF > + help > + Say yes here to build support for TI INA2xx family of Power Monitors. > + This driver is mutually exclusive with the HWMON version. > + > > > anything the patch should also add to hwmon/Kconfig (that will not lead to a cycling reference warning) ? > You could try the opposite, but I don't know if that works. depends on I2C && !INA2XX_ADC Guenter