Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933391AbbLBRVJ (ORCPT ); Wed, 2 Dec 2015 12:21:09 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:42276 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933335AbbLBRVE (ORCPT ); Wed, 2 Dec 2015 12:21:04 -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> <565F1FF8.5030508@roeck-us.net> <565F25D4.10006@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: <565F287A.3050103@roeck-us.net> Date: Wed, 2 Dec 2015 09:20:58 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <565F25D4.10006@baylibre.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4332 Lines: 112 On 12/02/2015 09:09 AM, Marc Titinger wrote: > On 02/12/2015 17:44, Guenter Roeck wrote: >> 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 > > I tried: it's functional, but leads to a ugly warning: > > drivers/iio/adc/Kconfig:173:error: recursive dependency detected! > drivers/iio/adc/Kconfig:173: symbol INA2XX_ADC depends on SENSORS_INA2XX > drivers/hwmon/Kconfig:1453: symbol SENSORS_INA2XX depends on INA2XX_ADC > Can't do that. > Anyone knows how to implement a radio button in Kconfig ? ;) > That is possible, but only in a single menu. Look for choice/endchoice. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/