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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b27580b05e
Коммит
d022a65ed2
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@ -52,6 +52,17 @@ static inline int32_t div_fp(int32_t x, int32_t y)
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return div_s64((int64_t)x << FRAC_BITS, y);
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}
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static inline int ceiling_fp(int32_t x)
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{
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int mask, ret;
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ret = fp_toint(x);
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mask = (1 << FRAC_BITS) - 1;
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if (x & mask)
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ret += 1;
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return ret;
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}
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struct sample {
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int32_t core_pct_busy;
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u64 aperf;
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@ -425,7 +436,7 @@ static void byt_set_pstate(struct cpudata *cpudata, int pstate)
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cpudata->vid.ratio);
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vid_fp = clamp_t(int32_t, vid_fp, cpudata->vid.min, cpudata->vid.max);
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vid = fp_toint(vid_fp);
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vid = ceiling_fp(vid_fp);
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if (pstate > cpudata->pstate.max_pstate)
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vid = cpudata->vid.turbo;
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