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Re: SCSI Polled io fixes for mac68k with PDMA enabled.
> I've found while working with mac68k that devices that require polled io scsi
> transfers would fail with sbc pdma (pseudo dma) would fail when reading and
> writing to the respective device.
>
> I've found that virtual devices for rascsi and the scsi2sd drives would fail
> using pdma. For virtual disks they would fail always when writing to the
> device, reads were ok.
>
> For virtual ethernet devices they would fail for reading and writing.
It looks more detailed information is necessary.
- How does it fail? Lost interrupts? Generic SCSI xfer errors?
- Does the mac68k sbc (with MI ncr5380sbc) work with other
real SCSI devices (at least on your machine)?
- Per obio/sbc_obio.c SBC_INTR and SBC_RESELECT are disabled
on MACIIFX and MACPB500 (maybe no working interrupts).
https://github.com/NetBSD/src/blob/43d029e4b58545fb46624a260279892a85d8a211/sys/arch/mac68k/obio/sbc_obio.c#L131
Does PDMA work on other machines (i.e. with working interrupts)?
- Furthermore, why do you check XS_CTL_POLL instead of SBC_INTR in
sc_options?
- Does the RaSCSI etc. work with GENERIC (not GENERICSBC)?
I don't know a history why mac68k has both MI ncr5380 (GENERICSBC) and
the own NCR5380 driver (GENERIC with dev/mac68k5380.c) for years.
- I wonder if these SCSI emulation devices using GPIO controled by
own software comply various xfer timings defined in SCSI spec.
(I have a drive with IDE-SCSI converter that emit errors
on news68k SCSI with MI ncr5380)
- I also wonder if the first byte of write xfer should be written on
manualy PDMA write, as eps_dma_go() in mac68k/obio/esp.c
https://github.com/NetBSD/src/blob/43d029e4b58545fb46624a260279892a85d8a211/sys/arch/mac68k/obio/esp.c#L564
---
Izumi Tsutsui
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