On Sun, 20 Nov 2005, Brad Boyer wrote:

> On Sun, Nov 20, 2005 at 05:23:16PM -0600, Bob Brose wrote:
> > With the b and c patches mentioned previously installed, if adb is
> > DISABLED esp and sonic work ok. sg_verify suceeds on the whole disc.
> >
> > If adb is enabled, sonic works ok but esp gets the selection errors
> > and fails the sg_verify randomly. ADB itself works with the keyboard
> > but is very flakey.
> >
> > With ADB enabled, If the kernel is compiled with gcc2.95 on OSX, there
> > are about 100 times as many esp select errors than there is if the
> > same kernel is compiled with gcc 3.3.5 on the performa itself.
> >
> > If I enable the "alternate irq mapping" by adding the 575 to the table
> > of supported machines in arch/m68k/mac/via.c I get MUCH better
> > behavior out of ADB keyboard. It SEEMS like I can't make it fail.
> > Sonic still works but esp throws many selection errors and fails right
> > away on sg_verify. The modified alt irq mapping code:
>
> This suggests to me that interrupts are getting lost. With the alternate
> IRQ mapping, the priorities are all different, so things are a lot less
> likely to overlap and cause problems.

With VIA 1 on interrupt level 6, ADB generally gets lower latency, which
kind of explains the improvement in ADB but not the additional
deterioration of SCSI caused by the alt_via_mapping change.

I don't know what to conclude from this other than ADB probably has more
than one race condition :-/

-f
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