Re: [RFC] i2c: Revert back to old device naming for ACPI enumerated I2C slaves

From: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
To: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Cc: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Jarkko Nikula
	<jarkko.nikula-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org,
	linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org,
	"Rafael J. Wysocki" <rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org>,
	Jean Delvare <jdelvare-IBi9RG/b67k@public.gmane.org>,
	Liam Girdwood <lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Dustin Byford
	<dustin-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org>
Subject: Re: [RFC] i2c: Revert back to old device naming for ACPI enumerated I2C slaves
Date: Tue, 25 Aug 2015 18:18:50 +0200	[thread overview]
Message-ID: <20150825161850.GA8118@katana> (raw)
In-Reply-To: <55DC8746.1060809-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>

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On Tue, Aug 25, 2015 at 08:18:30AM -0700, Guenter Roeck wrote:
> On 08/25/2015 07:57 AM, Wolfram Sang wrote:
> >On Tue, Aug 25, 2015 at 06:25:13AM +0100, Mark Brown wrote:
> >>On Mon, Aug 24, 2015 at 01:52:02PM +0300, Jarkko Nikula wrote:
> >>>Commit 70762abb9f89 ("i2c: Use stable dev_name for ACPI enumerated I2C
> >>>slaves") broke the lm-sensors which relies on I2C hwmon slave devices under
> >>>/sys/bus/i2c/devices/ to be named as "x-00yz". However if those hwmon
> >>>devices are ACPI 5 enumerated their name became "i2c-INTABCD:ij" and sysfs
> >>>code in lm-sensors does not find them anymore:
> >>
> >>Acked-by: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> >
> >Don't you think there will be regressions given that the new naming
> >scheme was around for 18 months?
> >
> 
> acpi is pretty long term. New bindings don't show up quickly.

The key is, there might be userspace applications that got used to our
new "export" of ACPI bindings. The bindings were already existing, our
"export" did change.

> So I am not surprised that this only shows up now.

I am, to be honest. It shows running lm-sensors with ACPI on a kernel
newer than 18 months. Not a rare scenario, so I thought.

> Will there be regressions ? Who knows. What we do know is
> that there are regressions today due to the original change.

Because we didn't pay enough attention. I wouldn't like to do the same
mistake again. Or?

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