From: David Gibson <david@gibson•dropbear.id.au>
To: linuxppc-embedded@lists•linuxppc.org
Subject: Re: very minor 405GP and 405GPr PCI difference
Date: Mon, 30 Sep 2002 14:01:43 +1000 [thread overview]
Message-ID: <20020930040143.GF10265@zax> (raw)
In-Reply-To: <OF8DC4E66D.5C36B7D3-ON87256C41.00434ACB@boulder.ibm.com>
On Fri, Sep 27, 2002 at 08:27:35AM -0400, Ralph Blach wrote:
>
> Yesterday I discovered a minor 405GP vs 405GPr PCI difference.
> IN the 405GP the ptm1ms bit 31, the enable bit for the region is set to 1
> by the hardware and cannot be written.
> On the 405GPr the bit is writable and this makes necessitates a change in
> walnut.c
>
> In walnut.c there is the line
>
> out_le32((void *) &(pcip->ptm1ms), 0x00000000);
>
> On the walnut, this would work fine because bit 31 cannot be written to a
> 0,
> On the GPr, this disables the regions and PCI no longer functions.
> The line should be changed to
>
> out_le32((void*)&(pcip->ptm1ms),0x000000001);
>
> This will fix the 405GPr and make no difference to the 405GP since the bit
> is permanently to 1.
I would put it more strongly than that: this is a bug, which we just
happen to get away with because of the behaviour of the 405GP.
The arrangement of the code in walnut.c suggests some confusion
between the PLB->PCI and PCI->PLB windows, which is probably the
origin of the bug (the fact that the 405GP numbers the former from 0
and the latter from 1 probably didn't help).
The fix you've suggested should be correct for Walnut, and probably
the other places that that code has been copied. I tend to think,
though, that this configuration of the 4xx PCI bridge should be moved
out of the board code and into ppc4xx_pci.c. If we do that, though we
should fully configure the PTMs, to wit:
out_le32((void *) &(pcip->ptm1ms), 0x00000000);
out_le32((void *) &(pcip->ptm1la), 0x00000000);
out_le32((void *) &(pcip->ptm1ms), 0x80000001);
out_le32((void *) &(pcip->ptm2ms), 0x00000000);
Which should configure the PCI bridge to match the comments in
walnut.c (i.e. map PCI addresses 0x00000000-0x7fffffff to
corresponding PLB addresses).
--
David Gibson | For every complex problem there is a
david@gibson•dropbear.id.au | solution which is simple, neat and
| wrong.
http://www.ozlabs.org/people/dgibson
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2002-09-30 4:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-27 12:27 very minor 405GP and 405GPr PCI difference Ralph Blach
2002-09-30 4:01 ` David Gibson [this message]
2002-10-01 5:21 ` David Gibson
2002-10-01 8:37 ` "David Müller (ELSOFT AG)"
2002-10-02 1:42 ` David Gibson
2002-10-02 4:26 ` Allen Curtis
2002-10-02 5:34 ` David Gibson
2002-10-02 17:03 ` Matt Porter
2002-10-03 1:10 ` David Gibson
2002-10-03 15:14 ` Matt Porter
2002-10-04 2:48 ` David Gibson
2002-10-04 18:33 ` Todd Poynor
2002-10-08 4:17 ` David Gibson
2002-10-08 19:39 ` Todd Poynor
2002-10-09 2:14 ` David Gibson
[not found] ` <20021 <20021023040850.GC1198@zax>
2002-10-24 23:50 ` Ralph Blach
2002-10-25 1:19 ` David Gibson
2002-10-02 7:46 ` "David Müller (ELSOFT AG)"
2002-10-03 1:12 ` David Gibson
2002-10-03 8:28 ` "David Müller (ELSOFT AG)"
2002-10-06 5:23 ` Andrew May
2002-10-07 1:31 ` Matt Porter
2002-10-08 4:14 ` David Gibson
2002-10-08 5:21 ` Andrew May
2002-10-08 14:56 ` Matt Porter
2002-10-08 17:31 ` Andrew May
2002-10-08 18:20 ` Matt Porter
2002-10-09 1:58 ` David Gibson
2002-10-09 10:35 ` Kenneth Johansson
2002-10-09 15:21 ` Allen Curtis
2002-10-11 19:37 ` Andrew May
2002-10-14 1:20 ` David Gibson
2002-10-08 6:19 ` Allen Curtis
2002-10-08 15:18 ` Matt Porter
2002-10-09 2:10 ` David Gibson
2002-10-22 21:55 ` Todd Poynor
2002-10-23 4:08 ` David Gibson
-- strict thread matches above, loose matches on Subject: below --
2002-10-23 13:10 Ralph Blach
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