Re: [hatari-devel] Regression in 2.0.0 RC1

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----- Nicolas Pomarède wrote:
> Le 27/10/2016 à 18:46, Anders Eriksson a écrit :
> 
> > Hello.
> >
> > Ok, have done all the above.
> >
> > I've tried on Hatari with 1.62 and 2.06.
> > I've tried on STe with 1.62 and 2.06.
> >
> > Register dumps are all zero, both 1.62 and 2.06.
> > The test program does not play noise on STe, but does on 2.0.0.
> >
> > Here are the small tools I made with source and the register dump files
> > (if you enjoy looking at 0's in a hexeditor).
> >
> > http://ae.dhs.nu/tmp/hdma.zip
> 
> thanks a lot ; that's strange.
> 
> I wonder if the DMA sound doesn't output anything after a reset until 
> something is really written to dma start and/or end addresses ?
> 
> Could you test this too ?
> 
>   - after reset, write 0 to ff8907 (even if it's already 0), then write 
> to ff8901 / 8924 / 8922 as before to start dma sound. Do you get sound ?
> 
>   - after reset, write $40 (!=0) for example to $ff8907, do you get 
> sound then if you write to ff8901 / 8924 / 8922
> 
>   - in case you didn't had sound after writing to $ff8907, then write 
> $40 to $ff8907 and also write $50 to $ff8913 (end address), then write 
> to ff8901 / 8924 / 8922. Do you get sound ? (you should)
> 
> 
> Depending on these, one possible fix in Hatari could be to disable STE 
> dma sound until a write is really made to start and/or end address, but 
> I'm not sure this is how the real STE behaves.
> 
> 
> Or maybe it's the microwire volume after reset which is set too high 
> under Hatari should be 0 ? Unfortunatelly, it's not possible to read 
> microwire regs content.
> 
LMC1992 Data Sheet: ("General Description" p.1 para.3)
'Volume and fader are at minimum and tone controls are flat 
when supply voltage is first applied.'

Hatari should (and probably does) set the fader registers to zero,
and each of the bass+treble registers to 6 on a cold start.
Reset does not affect the LMC1992 registers as the LMC1992
has no reset line.
>
> So, I'm thinking at another test (instead of doing the above ones) : if 
> you just "move.b #1,$ffff8901.w" after a reset and read $ff8909/0b/0d a 
> few times, does the current dma address changes ?
> If so, it would mean that DMA is really started but that's the volume is 0
> 
> 
> 
> Nicolas
> 
> 




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