Issues with A3720 PCIe controller driver pci-aardvark.c

[Pali Rohár]

+ Bharat, Veerasenareddy and Wojciech from Marvell

Hello! Could you please look at this email and help us with this Marvell HW issue?

On Saturday 24 July 2021 00:17:10 Pali Rohár wrote:
> Hello Konstantin!
> 
> There are issues with Marvell Armada 3720 PCIe controller when high
> performance PCIe card (e.g. WiFi AX) is connected to this SOC. Under
> heavy load PCIe controller sends fatal abort to CPU and kernel crash.
> 
> In Marvell Armada 3700 Functional Errata, Guidelines, and Restrictions
> document is described erratum 3.12 PCIe Completion Timeout (Ref #: 251)
> which may be relevant. But neither Bjorn, Thomas nor me were able to
> understood text of this erratum. And we have already spent lot of time
> on this erratum. My guess that is that in erratum itself are mistakes
> and there are missing some other important details.
> 
> Konstantin, are you able to understand this erratum? Or do you know
> somebody in Marvell who understand this erratum and can explain details
> to us? Or do you know some more details about this erratum?
> 
> Also it would be useful if you / Marvell could share text of this
> erratum with linux-pci people as currently it is available only on
> Marvell Customer Portal which requires registration with signed NDA.
> 
> In past Thomas wrote patch "according to this erratum" and I have
> rebased, rewritten and resent it to linux-pci mailing list for review:
> https://lore.kernel.org/linux-pci/20210624222621.4776-6-pali@kernel.org/
> 
> Similar patch is available also in kernel which is part of Marvell SDK.
> 
> Bjorn has objections for this patch as he thinks that bit DIS_ORD_CHK in
> that patch should be disabled. Seems that enabling this bit effectively
> disables PCIe strong ordering model. PCIe kernel drivers rely on PCIe
> strong ordering, so it would implicate that that bit should not be
> enabled. Which is opposite of what is mentioned patch doing.
> 
> Konstantin, could you help us with this problem?