lkml.org 
[lkml]   [2002]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Flash Back -- kernel 2.1.111
On Sun, Feb 24, 2002 at 11:51:13PM +0100, Vojtech Pavlik wrote:
> On Sun, Feb 24, 2002 at 02:44:23PM -0800, David S. Miller wrote:
>
> > From: Vojtech Pavlik <vojtech@suse.cz>
> > Date: Sun, 24 Feb 2002 23:39:37 +0100
> >
> > > > happens if you plug in a 66MHz non-capable card to the 50 MHz bus.
> > >
> > > The bus speed drops to 33MHz.
> >
> > Interesting. I'd expect 25 myself ... then we'll definitely need two
> > clock values in struct pci_bus - because the hi-speed one isn't always a
> > double the low one - as shown by your example.
> >
> > You only need one, the current active one.
> >
> > If you think that hot-plug is an issue, the arch dependant could would
> > need to recalculate the "current bus speed" and all would be fine.
> >
> > So why do we need two values?
>
> Oh, you're right. We indeed need only one.
>
> Hmm, now hotplug changing the PCI clock would be quite a lot of fun -
> all running drivers will need to know about the change, because some may
> need to recompute the timings they have programmed into the chips ...
>
> Because virtually disconnecting and reconnecting all the cards for which
> the timings have changed will probably not be an option.

Personally, I think hot-plugging a 33mhz pci device into a 66mhz pci bus
with other active devices on it is either user error or designer error
(should have had a bridge), and a 'virtual disconnect and reconnect' is
reasonable.

You're going to kill (or at least stop) any transactions going on on the
bus while you're physically hot-plugging anway..

--
Troy Benjegerdes | master of mispeeling | 'da hozer' | hozer@drgw.net
-----"If this message isn't misspelled, I didn't write it" -- Me -----
"Why do musicians compose symphonies and poets write poems? They do it
because life wouldn't have any meaning for them if they didn't. That's
why I draw cartoons. It's my life." -- Charles Schulz
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:24    [W:0.594 / U:0.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site