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Subject: Re: [PATCH] r8169: don't use MSI-X on RTL8106e
To:     David Miller <davem@davemloft.net>
Cc:     helgaas@kernel.org, jian-hong@endlessm.com, nic_swsd@realtek.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux@endlessm.com, linux-pci@vger.kernel.org,
        marc.zyngier@arm.com, tglx@linutronix.de, hch@lst.de
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 <20180821.123108.89921430801253333.davem@davemloft.net>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <da97e198-7683-e0ff-92a9-3b1b22da3757@gmail.com>
Date:   Tue, 21 Aug 2018 22:48:29 +0200
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On 21.08.2018 21:31, David Miller wrote:
> From: Heiner Kallweit <hkallweit1@gmail.com>
> Date: Mon, 20 Aug 2018 22:46:48 +0200
> 
>> I'm in contact with Realtek and according to them few chip versions
>> seem to clear MSI-X table entries on resume from suspend. Checking
>> with them how this could be fixed / worked around.
>> Worst case we may have to disable MSI-X in general.
> 
> I worry that if the chip does this, and somehow MSI-X is enabled and
> an interrupt is generated, the chip will write to the cleared out
> MSI-X address.  This will either write garbage into memory or cause
> a bus error and require PCI error recovery.
> 
> It also looks like your test patch doesn't fix things for people who
> have tested it.
> 
The test patch was based on the first info from Realtek which made me
think that the base address of the MSI-X table is cleared, what
obviously is not the case.

After some further tests it seems that the solution isn't as simple
as storing the MSI-X table entries on suspend and restore them on
resume. On my system (where MSI-X works fine) MSI-X table entries
on resume are partially different from the ones on suspend.

Unfortunately I don't have affected test hardware, currently I'm
waiting for further feedback from Realtek.

> Hmmm...
>