G3 Upgrade Questions....

Takayuki Yamaizumi zumi at yamato.ibm.co.jp
Fri Jul 30 11:38:52 EST 1999

  Hi, Adrian,

  Thanks for your advice,

adrian> I'm a little confused by this patch, because it is very different from
adrian> Motorola's application note AN1800/D (Programming the Thermal Assist
adrian> Unit in the MPC750 Microprocessor). 

adrian> http://www.mot.com/SPS/PowerPC/teksupport/teklibrary/appnotes/an1800.pdf

  I've never checked that document, so I download it (but, today I
have no spare time for reading, sorry). That patch is based on
cpu_temp in the older vger kernel which was commented out in 2.1.119
(or around this version, I remember. And still being commented out in
the latest kernel.) and have been created only using Motorola's
"PowerPC 750 User's Manual"

as reference. 

adrian> 1) No calibration. The board vendor is supposed to calibrate the TAU
adrian> before shipping the board, then supply the calibration value. I'm not
adrian> sure whether Apple do this.
adrian> 2) Why all the time spent doing bit reversals? Why not just fix the
adrian> broken values in processor.h and test the correct bits to start with?

  Currently, I don't care about the definition in
include/asm-ppc/processor.h, but should be fixed if broken. I also
have been confusing why bit reversal is needed for reading
"reasonable" value of tempearture.

Takayuki Yamaizumi
Software Development Lab, IBM Japan.
E-mail: ty at tokusen.org, ty at kamoi.imasy.or.jp (Home)
        zumi at yamato.ibm.co.jp (Office)

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