Subject: Re: [PATCH 2/2] PCI: armada8k: don't toggle reset twice

From: Baruch Siach <[email-masked]>
Date: Thu, 10 Jan 2019 15:05:49 +0200

Hi Andrew,

On Thu, Jan 10 2019, Andrew Lunn wrote:
> On Thu, Jan 10, 2019 at 02:26:22PM +0200, Baruch Siach wrote:
>> Commit 3d71746c42 ("PCI: armada8k: Add support for gpio controlled reset
>> signal") added reset signal support. Reset is unconditionally asserted
>> and deasserted.
>>
>> Unfortunately, that commit breaks boot on Macchiatobin when a Mellanox
>> NIC is in the PCIe slot.
>>
>> It turns out that you can toggle the reset signal only once. Another
>> reset signal toggle makes access to PCI configuration registers stall
>> indefinitely. U-Boot toggles the Macchiatobin PCIe reset line already at
>> boot.
>
> Hi Baruch
>
> Is this double reset issue limited to just Mellanox NICs, or any
> device in the PCIe slot?
>
> This sounds more like a workaround than a fix. It would be good to
> investigate further and determine which end of the PCIe link has the
> problem.

Sven Auhagen reported the same issue with Intel NIC attached to
mini-PCIe slots on a custom Armada 8K design.

How would you suggest to investigate this issue?

baruch

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