Hi Frank, On Fri, 15 Aug 2008 08:00:13 -0400, Frank Myhr wrote: > Jean Delvare wrote: > > - case 24: /* AMD NPT 0Fh (Athlon64 & Opteron) */ > > + case 24: /* Athlon64 & Opteron */ > > + val &= 0x1f; > > + if (val == 0x1f) > > + return 0; > > Nice catch that all bits set is an error (voltage "off", impossible if code is > running) for the 5-vid-bit cpu's but not the 6-vid-bit ones in case 25 Not necessarily impossible. Think of hot-pluggable CPUs... > > + /* fall through */ > > + case 25: /* AMD NPT 0Fh */ > > val &= 0x3f; > > return (val < 32) ? 1550 - 25 * val > > : 775 - (25 * (val - 31)) / 2; > > The above formula is correct, and I'm the one who put it here in this form. But > in looking at AMD cpu specs yesterday I came across: > > AMD 31116, BIOS and Kernel Developer's Guide (BKDG) For AMD Family 10h Processors > http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31116.PDF > section 2.4.1.5.2, p. 30 > > This gives the canonical formula for K10's, which happens to be the same as for > the 6-vid-pin K8's: > > return (val >= 0x20) ? (7625 - 125 * (val - 0x20)) / 10 > : 1550 - 25 * val; > > This gives the same result and is easier to compare with the AMD reference > above. Perhaps we should make this change, I'll leave it up to you. Why not, but let's not push this now. We're already late in the release cycle, all we want to do at this point is fix regressions in the code. So, feel free to send an incremental patch changing the formula in the code; we can have this in kernel 2.6.28. -- Jean Delvare
