From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jesse Barnes <jbarnes@virtuousgeek.org>
Subject: Re: [PATCH 5/7] drm/i915: Add setters for min/max
	frequency
Date: Thu, 6 Sep 2012 14:48:03 -0700
Message-ID: <20120906144803.3dcc1832@jbarnes-desktop>
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To: Ben Widawsky <ben@bwidawsk.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, intel-gfx@lists.freedesktop.org, Jacob Pan <jacob.jun.pan@linux.intel.com>, Arjan van de Ven <arjan@linux.intel.com>
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On Thu,  6 Sep 2012 13:54:08 -0700
Ben Widawsky <ben@bwidawsk.net> wrote:

> Provide a standardized sysfs interface for setting min, and max
> frequencies.  The code which reads the limits were lifted from the
> debugfs files. As a brief explanation, the limits are similar to the CPU
> p-states. We have 3 states:
> 
> RP0 - ie. max frequency
> RP1 - ie. "local min" frequency

I'd say "preferred min" or "vmin" here instead.

> RPn - seriously lowest frequency
> 
> Initially Daniel asked me to clamp the writes to supported values, but
> in conforming to the way the cpufreq drivers seem to work, instead
> return -EINVAL (noticed by Jesse in discussion).
> 
> The values can be used by userspace wishing to control the limits of the
> GPU (see the CC list for people who care).

Can you add this and any other i915 bits that are missing to the sysfs
documentation under Documentation/?

Thanks for moving to -EINVAL, it makes a lot more sense to me.

-- 
Jesse Barnes, Intel Open Source Technology Center