lkml.org 
[lkml]   [1998]   [Nov]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: UDMA is NFG on Ultra33 (CMD646 in disguise)
pmonta@halibut.imedia.com wrote:
..
> Do you also see problems with the normal, non-UDMA busmaster
> operation? If there is a PCI-controller bug for this chip,
> likely enough any busmaster mode would be bad.
>

Okay, here's the latest scoop:

UDMA2: corruption
UDMA1: not tried
UDMA0: no corruption
DMA2: no corruption (identical timings to UDMA0/PIO4)
PIO4: no corruption (identical timings to DMA2/UDMA0)

Looks like we could put together a kernel patch to auto-detect
the card, and automatically convert UDMA2 settings to UDMA0
to prevent data corruption.

Easy to do for the chipset, but the drive also needs to be told,
via "hdparm -X64".

PROBLEM: some drives require a reset (?) when changing UDMA modes.
Ugh.

Maybe for linux-2.1.xxx, we should just have the kernel auto-detect
the chipset, check for UDMA > 0, and not use DMA if the chipset is
programmed for UDMA > 0.

The user can then later correct this using /proc/ide/*/config and hdparm.

For linux-2.3.xxx, we can add significantly more functionality to
to the kernel to do all this automatically.
--
mlord@pobox.com

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:45    [W:0.110 / U:0.332 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site