Slave IDE HDD not working in UDMA5

[Bruce Evans]

On Thu, 16 Jun 2005 scuba at centroin.com.br wrote:

> 	This was first posted on freebsd-question, but I could not find
> the solution yet.
> 	Maybe you could help me.

Maybe a little.  I don't use 5.4...

> 	I´ve installed FreeBSD 5.4 on a new machine with the following
> hardware:
>
> 	Asus P4P800 SE  (BIOS v. 1008)
> 	2GB RAM ( 4x 512 DDR400 )
> 	2 HDD Samsung SP0802N (80GB 7200rpm ata-100) 80 pins cable.
>
> 	The HD were formated with newfs defaults, and the following
> results were the same using both as master (primary e secondary) or with a
> master / slave (same interface).
>
> 	With diskinfo both performance are the same, but with "dd", the
> second disc (the slave or the secondary master), is always worst as if it
> were working in DMA2.

I remember a commit to the ata driver to fix misprogramming of DMA timing 
on an Intel chipset for devices and/or channels other than the first.  I'm
not sure if 5.4 has the bug or the fix.

diskinfo only tests reading, and you only showed a dd test using writing
(to a file), so the problem is apparently only that writing to the second
drive is slow.

> 	what should be the right results?

Swap the devices to see if it is a drive problem (unlikely with the
same model of drive but...  I have one system that apparently has
worse timing on the secondary channel.  This showed up as writes
causing subsequent reads to be slow -- apparently the writes caused
some errors and error correction as perfect except for slowing things
down).

Bruce