From: Dirk Brandewie <dirk.j.brandewie@intel.com>
Date: Mon, 13 Oct 2014 15:37:44 +0000 (-0700)
Subject: intel_pstate: Correct BYT VID values.
X-Git-Tag: fixes-against-v3.18-rc2~13^2^3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d022a65ed2473fac4a600e3424503dc571160a3e;p=pandora-kernel.git

intel_pstate: Correct BYT VID values.

Using a VID value that is not high enough for the requested P state can
cause machine checks. Add a ceiling function to ensure calulated VIDs
with fractional values are set to the next highest integer VID value.

The algorythm for calculating the non-trubo VID from the BIOS writers
guide is:
 vid_ratio = (vid_max - vid_min) / (max_pstate - min_pstate)
 vid = ceiling(vid_min + (req_pstate - min_pstate) * vid_ratio)

Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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