# Slow DTC3181 aka UDS-IS11 SCSI card with Domex 436P chip

Niko =?iso-8859-1?Q?Mikkil=E4?= (ntmikki@sci.fi)
Tue, 08 Jun 1999 10:35:15 +0000

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Hi

I'm still trying to figure out, why this adapter doesn't work properly
under Linux. Few days ago someone wrote about the same problem with
Mustek ScanExpress 12000SP as I have with UMAX Astra 1200S: scanning is
about 10 times slower than with Windows 95 drivers.

Both scanners have the same SCSI card, DTC3181, which is supported in
Linux kernel (g_NCR5380 driver). As far as I know the card _has_ IRQ. In
PNP mode it's IRQ 3. The lack of DMA channel makes the card so slow.

This is what cat /proc/scsi/g_NCR5380/0 gives:

SCSI host number 0 : Generic NCR5380/NCR53C400 Scsi Driver
Generic NCR5380 driver version 1
NCR5380 core version 7
NO NCR53C400 driver extensions
Using port mapping at port 0x300, on interrupt 3
REQ not asserted, phase unknown.
No currently connected command
issue_queue
disconnected_queue

I've tried to optimize the driver for my scanner by:

1) Increasing the SG_BIG_BUFF size in header /usr/include/scsi/sg.h and
recompiling SANE (Umax backend)
- Doesn't give better results

2) Uncommenting USLEEP settings in kernel sources
/drivers/scsi/g_NCR5380.c
- Gives more speed, but still not fast enough.

3) Trying different USLEEP values.
- Locked up my machine few times. Haven't found good combinations.

It isn't a buffer problem, I think, because when using 300 dpi it takes
twice the time to scan a 3000 kb image than to scan 3000 kb image with
100 dpi.
I guess that by testing different USLEEP settings it would be possible
to get better performance. Has anyone tried?

So if there's someone out there who has this damn adapter working,
PLEASE tell the rest of us!!!

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