Subject: Re: r8169 regression in 2.6.26.3 vs 2.6.26.2
From: Pascal Terjan <pterjan@mandriva.com>
To: Francois Romieu <romieu@fr.zoreil.com>
Cc: Marcus Sundberg <marcus@ingate.com>,
       linux-kernel <linux-kernel@vger.kernel.org>, stable@kernel.org
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	 <20080827201111.GA29569@electric-eye.fr.zoreil.com>
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Organization: Mandriva
Date: Fri, 29 Aug 2008 19:51:07 +0200
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Le mercredi 27 ao?t 2008 ? 22:44 +0200, Pascal Terjan a ?crit :
> Le mercredi 27 ao?t 2008 ? 22:11 +0200, Francois Romieu a ?crit :
> > Pascal Terjan <pterjan@mandriva.com> :
> > > Le mercredi 27 ao?t 2008 ? 12:38 +0200, Marcus Sundberg a ?crit :
> > > > Pascal Terjan wrote:
> > > > > Since updating to 2.6.26.3, networking no longer works on Acer Aspire
> > > > > One.
> > > > > 
> > > > > PCI config is now always filled with ones.
> > > > > 
> > > > > Reverting "r8169: avoid thrashing PCI conf space above
> > > > > RTL_GIGA_MAC_VER_06" makes it work again.
> > > > > 
> > > > > The device is 10ec:8136
> > [...]
> > > > How does the kernel identify your chipset upon driver load?
> > > > (grep for XID)
> > > 
> > > eth0: RTL8169 at 0xe04ee000, 00:1e:68:a0:07:b5, XID 24a00000 IRQ 17
> > 
> > As far as I can read rtl8169_get_mac_version, this XID should not match
> > any known device with 2.6.26.3 and thus fallback to RTL_GIGA_MAC_VER_01
> > (assuming that rtl8169_init_phy runs after rtl8169_get_mac_version, what
> > it appears to do so far).
> > 
> > Yes / no / -ECOFFEE ?
> > 
> 
> Yes I took some time to look at it and now does not understand what's
> wrong.
> 
> Indeed I get "unknown MAC (27a00600)" so I get RTL_GIGA_MAC_VER_01 which
> is <= RTL_GIGA_MAC_VER_06, so it should work fine with or without this
> patch. And indeed it seems to work when I rebuild the module, even when
> I do not revert the patch.
> 
> And by the way, unrelated to this problem, it is written twice for
> RTL_GIGA_MAC_VER_02:
> 
> =====
>         if (tp->mac_version <= RTL_GIGA_MAC_VER_06) {
>                 dprintk("Set MAC Reg C+CR Offset 0x82h = 0x01h\n");
>                 RTL_W8(0x82, 0x01);
>         }
> [...]
>         if (tp->mac_version == RTL_GIGA_MAC_VER_02) {
>                 dprintk("Set MAC Reg C+CR Offset 0x82h = 0x01h\n");
>                 RTL_W8(0x82, 0x01);
> =====
> 
> To come back to the problem, this patch may not be faulty but I fail to
> understand the issue...
> 
> - 2.6.26.2 always works
> - 2.6.26.3 from my distro always fails
> - 2.6.26.3 from my distro with r8169 rebuilt out of the kernel tree but
> from the same source and with the same config, gcc, etc, works...
> 
> So either it is random I am very unlucky that it always works with one
> and always fails with the other or there is some difference that I could
> not think about

OK I was very unlucky...
For some reason when 2.6.26.2 was OK but 2.6.26.3 built inside the rpm
will always fail (or maybe very often, harder to test).
And when rebuilding the module by hand, it will work most of the time,
but I got the bug after unloading/reloading it about 30 times in a row,
so it's just that this chip is affected by the random bug and something
make it more likely to happen.

> > On a different topic, I would suggest to try patches #0001 ... #0006
> > at http://userweb.kernel.org/~romieu/r8169/2.6.27-rc3/20080818/ with
> > your chipset.
> 
> OK I will

I applied these patches meaning that now the write will not occur, and
tried to unload/load the module 200 times but after some time I got a
oops in rtl_tx_performance_tweak (and could not capture it).

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