Fwd: confusion about libata.force=80c

["Tom Sylla" <tsylla@gmail.com>]

Anyone have a comment? All I am asking for now is if this *should*
work or not. Is force=80c supposed to do what I want?


---------- Forwarded message ----------
From: Tom Sylla <tsylla@gmail.com>
Date: Wed, May 14, 2008 at 2:20 PM
Subject: confusion about libata.force=80c
To: linux-ide@vger.kernel.org


I have a platform with a single CompactFlash socket connected to a
Broadcom HT1000's PATA port. With libata's pata_serverworks, it ends
up using drive-side 80-conductor cable detection (Broadcom provides no
cable bits for the BIOS to report what is attached). The
CompactFlashes I am using mis-report the cable type, and
pata_serverworks limits to UDMA2. I tried to use the recent addition
of libata.force, but it does not seem to work like I would expect it
to. An excerpt from dmesg:

scsi4 : pata_serverworks
scsi5 : pata_serverworks
ata5: PATA max UDMA/66 cmd 0x1f0 ctl 0x3f6 bmdma 0xffa0 irq 14
ata6: PATA max UDMA/66 cmd 0x170 ctl 0x376 bmdma 0xffa8 irq 15
ata5: FORCE: cable set to 80c
ata5.00: ATA-4: CF CARD, 20080308, max UDMA/66
ata5.00: 15662304 sectors, multi 0: LBA
ata5.00: limited to UDMA/33 due to 40-wire cable
ata5.00: configured for UDMA/33

The force parameter is certainly getting accepted, but then 3 lines
later, it believes it has a 40 conductor cable.

I have attached the full dmesg. This is vanilla 2.6.25.3 with "options
libata force=80c" added in the initrd.

Yes, I know I should just get a more well-behaved device, but both of
the high-speed (UDMA) CFs I am using mis-report the cable detection. I
would bet many other high-speed CFs do the same. I have already
contacted the CF manufacturer to look into it. For now, though, I'd
like to run UDMA4, and the force parameter seems like it would do what
I want.

Is force=80c what I want? Should it work?

Thanks