Subject: SCSI problems

From: Thomas Bogendoerfer <[email-masked]>
Date: Sat, 5 Sep 1998 22:33:07 +0200

I'm trying to narrow down the SCSI problems, which some people are seeing.
I did some test with a DAT drive and got also problems. Right now my Indy
is running with a normal kernel but with SCSI dma disabled. And I didn't
see any problems. So could anybody try to start the kernel with following
setup option added:

wd33c93=nodma:1

Of course this decreases the SCSI speed, but I want know, if we get rid
of the problems. If I'm on the right track, I suspect some problems with
DMA/cache flushing.

Thomas.

-- 
See, you not only have to be a good coder to create a system like Linux,
you have to be a sneaky bastard too ;-)
                   [Linus Torvalds in <[email-masked]>]

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From: Thomas Bogendoerfer <[email-masked]>
Date: Sun, 6 Sep 1998 11:37:15 +0200

On Sun, Sep 06, 1998 at 10:54:52AM +0200, Ulf Carlsson wrote:
> On Sat, 5 Sep 1998, Thomas Bogendoerfer wrote:
> Which processor do you have, e.g. which dma_cache_wback_inv procedure are
> you making use of? 

it's a R4600 with second level cache. So it should use 
r4k_dma_cache_wback_inv_sc(), too.

Thomas.

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From: [email-masked]
Date: Mon, 7 Sep 1998 01:23:31 +0200

> r4k_dma_cache_wback_inv_sc(), too.

The R4600 _CPU_ doesn't support an l2 cache therefore the *_pc variants are
being used.  The l2 cache on the indy CPU module is handled by the logic on
the CPU _module_; the code to deal with that is being called by the *_pc
functions and is in arch/mips/sgi/kernel/indy_sc.c.

  Ralf