linux-kernel - Re: [PATCH] b44: power down PHY when interface down

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Message-Id: <200707011729.59673.mb@bu3sch.de>
Date:	Sun, 1 Jul 2007 17:29:59 +0200
From:	Michael Buesch <mb@...sch.de>
To:	Lennert Buytenhek <buytenh@...tstofly.org>
Cc:	Török Edvin <edwintorok@...il.com>,
	zambrano@...adcom.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, power@...host.org
Subject: Re: [PATCH] b44: power down PHY when interface down

On Sunday 01 July 2007 17:00:06 Lennert Buytenhek wrote:
> On Sun, Jul 01, 2007 at 12:23:16PM +0200, Michael Buesch wrote:
> 
> > > More or less.  You can't add the resistances like that, since the
> > > bus isolation chip buffers the IDSEL signal, but it is correct that
> > > if the host's IDSEL resistor is larger than a certain value, the
> > > combination of the resistive coupling of IDSEL plus the extra buffer
> > > in the isolator might be causing the IDSEL input on the 'guest' PCI
> > > board to assert too late (or not assert at all), causing config
> > > accesses to fail.
> > > 
> > > (This also depends on the specific 'guest' PCI board used, as you
> > > noted, due to differing IDSEL trace lengths/capacitances and input
> > > pin capacitances on different PCI boards.  Also, it might work at
> > > 33 MHz but not work at 66 MHz, etc.)
> > 
> > It doesn't work on any of my boards :(
> 
> What extender board is this?  Do you have docs/schematics?

catalyst pcibx32
http://bu3sch.de/pcibx.php
Docs yes, schematics no.

> And what motherboard brand/type?

ABit AI7
The other was some MSI and some very old random board. dunno.
It works perfectly fine with other cards, like a linksys
wlan card with a broadcom 4318 chip. It's just the b44
that doesn't work in the extender.

> Actually, the IDSEL resistor would be on the computer's
> motherboard, not on the PCI board.  And to which address line

Yeah, I know.

> the IDSEL line is connected depends on which PCI slot on the
> motherboard you're looking at.

Sure.

> A multimeter should do the trick, but I would advise against this
> if you're not totally comfortable with hacking hardware.

Well, you mean to measure the idsel against each possible AD line?
It's difficult, because the motherboard is inside of a standard
computer case and a watercooling system is mounted. So I would
have to disassemble all that stuff. :/
Probably I can measure it with very thin probes on the slots
without unmounting the board, hm...

-- 
Greetings Michael.
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