2742T problems

[Doug Ledford]

--------

> Ahh.  It's all coming back to me now.  STPWEN only affects aic78xx chips.
> I believe that the termination is handled completely by external logic
> for the aic7770 and it may just be that SCSICONF isn't a scratch ram
> location only on the aic7770.  I'll have to go find my design in handbook
> and tech ref to be sure.

This is exactly the problem with the 2742 cards.  STPWEN in SXFRCTL1 does 
nothing about termination.  0x80 in SCSICONF and SCSICONF + 1 control the 
termination on the 2742 cards (I don't know about 2842, but I doubt it since 
we set termination via the BRDCTL register).  In any case, the second 
problem related to this is that one of the new registers used for the 
sequencer lock (FIFODEPTH) and ARG1/RETURN1 overlap SCSICONF and SCSICONF + 
1.  Hence our termination was getting overwritten.  I modified the 
aic7xxx.reg file so that CMDOUTCNT and FIFODEPTH are the only registers that 
overlap in the space of 0x05a to 0x05f.  Then, I modified the sequencer so 
that on cards that don't have paging enabled (all 2742 and 2842 cards, as 
set by detect_maxscb() ), we don't *ever* touch those register except when 
they are referenced as SCSICONF and treated accordingly.  I verified that 
the non-paging version of the sequencer will not touch these register 
locations either.  This change makes the 2742 cards work again.  Enclosed is 
a patch against 2.0.31-pre-10.  It fixes this problem in the aic7xxx.reg 
file, aic7xxx_reg.h and aic7xxx_seq.h, adds the proper check for 
PAGE_ENABLED in the aic7xxx.c file, and fixes one off by one error in 
aic7xxx.c and fixes one ommission error in aic7xxx_proc.c.

NOTE: anyone having problems with the 2742 cards, as well as all other 
aic7xxx users should test this patch!  I don't like unexpected suprises.  So 
far I've verified it on a 2940UW and a 2742T, but others should try it as 
well.  It will only apply cleanly against 2.0.31-pre-10 since some off by 
one error fixes and a fix to aic7xxx_proc.c went into pre-10.



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