tree 6ff152f13f0ce8918e97ecd968fd7d3fabf13fcf
parent b27580b05e6f5253228debc60b8ff4a786ff573a
author Dirk Brandewie <dirk.j.brandewie@intel.com> 1413214664 -0700
committer Rafael J. Wysocki <rafael.j.wysocki@intel.com> 1414098000 +0200

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>