Subject: Re: [PATCH v2] Re: Battery class driver.
From: David Zeuthen <davidz@redhat.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Shem Multinymous <multinymous@gmail.com>,
       Richard Hughes <hughsient@gmail.com>, Dan Williams <dcbw@redhat.com>,
       linux-kernel@vger.kernel.org, devel@laptop.org, sfr@canb.auug.org.au,
       len.brown@intel.com, greg@kroah.com, benh@kernel.crashing.org,
       linux-thinkpad mailing list <linux-thinkpad@linux-thinkpad.org>
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Date: Sat, 28 Oct 2006 10:55:37 -0400
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On Sat, 2006-10-28 at 15:36 +0100, David Woodhouse wrote:
> On Sat, 2006-10-28 at 16:34 +0200, Shem Multinymous wrote:
> > * Thou shalt not export any attributes in sysfs except these, and
> >     with these units: */
> > 
> > Drivers *will* want to violate this. For example, the "inhibit
> > charging for N minutes" command on ThinkPads seems too arcane to be
> > worthy of generalization. I would add a more sensible boolean
> > "charging_inhibit" attribute to battery.h, and let the ThinkPad driver
> > implement it as well as it can. The driver will then expose a
> > non-stadard "charging_inhibit_minutes" attribute to reveal the finer
> > level of access to those who care.
> 
> If it makes enough sense that it's worth exporting it to userspace at
> all, then it can go into battery.h.

If it's non-standard please make sure to prefix the name with something
unique e.g.

 x_thinkpad_charging_inhibit [1]

to avoid collisions, e.g. two drivers using the same name but the
semantics are different. Over time the battery class can standardize on
this (if a feature becomes sufficiently common) and drivers can move
over if they want to.

    David

[1] : The x_ bit is inspired by how non standard email headers are
handled e.g. X-Mailer and whatever. It's a very useful hint to user
space people (and users in general) that some sysfs attribute is
non-standard. I was going to suggest to user a full reverse DNS style
naming scheme but I guess something that is unique enough will do.


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