Re: DMA CRC errors with SiS chipset and notebook drive

[Chuck Lever <chuck.lever@oracle.com>]

Alan Cox wrote:
> > Aug  9 07:41:29 monet kernel: ata1.00: limiting speed to UDMA/66:PIO4
> > Aug  9 07:41:29 monet kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr
> > 0x0 action 0x2
> > Aug  9 07:41:29 monet kernel: ata1.00: (BMDMA stat 0x64)
> > Aug  9 07:41:29 monet kernel: ata1.00: cmd
> > c8/00:08:fb:7c:a1/00:00:00:00:00/e0 tag 0 cdb 0x12 data 4096 in
> > Aug  9 07:41:29 monet kernel:          res
> > 51/84:00:00:00:00/00:00:00:00:00/e0 Emask 0x10 (ATA bus error)
> > Aug  9 07:41:29 monet kernel: ata1: soft resetting port
> > Aug  9 07:41:29 monet kernel: ata1.00: configured for UDMA/66
> > Aug  9 07:41:29 monet kernel: ata1.01: configured for UDMA/33
> > Aug  9 07:41:29 monet kernel: ata1: EH complete
>
> Drops to UDMA33 for 40 wire cable.

It drops from UDMA/100 to UDMA/66 for the disk, but stays at UDMA/33 for 
the optical drive.  If I have only the disk on that controller, the disk 
still drops to UDMA/66.

> Looks to me like your cabling is out of spec or you have electrical noise
> problems.

I've tried different cabling solutions, including round and flat IDE 
cables.  What might cause "electrical noise"?  Are 44-40 pin adapters 
reliable?
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