> > Could you try to force it to 1-sector PIO transfer ?
> > Just force wd->sc_multi to 1 in wd.c:wdattach() line 326
> 
> This fixes the problem.  So I guess the Samsung cards are lying when they
> claim to support 4-sector transfers?  Or is there a bug in the NetBSD driver
> or something?

(not having looked at the code)

What does 'wd->sc_multi' control?
IIRC there are two different commands, one for 'normal' reads and one
for multi-sector reads.  However a 'normal' read command can transfer
many sectors.

The multi-sector read reduces the number of interrupts by transferring
data in blocks of sectors (instead of single sectors).
I wouldn't have thought that multi-sector reads would make a big difference.

(Interestingly I did find it worth taking the interrupts for read data
on CF cards - you might think it would be worth polling...)

	David

-- 
David Laight: david@l8s.co.uk