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Date:   Sat, 17 Apr 2021 11:31:08 +0200
From:   Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
To:     Keith Busch <kbusch@kernel.org>
Cc:     linux-pci@vger.kernel.org,
        Marek =?utf-8?B?QmVow7pu?= <kabel@kernel.org>
Subject: Re: PCIe: can't set Max Payload Size to 256
Message-ID: <20210417093108.uspm6e6h46k655p2@pali>
References: <20210416173119.d2eq2zetzp5awunj@pali>
 <20210416202941.GB32082@redsun51.ssa.fujisawa.hgst.com>
 <20210416230430.cdzlnifaenzhbsmm@pali>
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On Saturday 17 April 2021 11:29:04 Keith Busch wrote:
> On Sat, Apr 17, 2021 at 01:04:30AM +0200, Pali Rohár wrote:
> > Above NVMe disk is connected to PCIe packet switch (which acts as pair
> > of Upstream and Downstream ports of PCI bridge) and PCIe packet switch
> > is connected to the Root port.
> > 
> > I'm not sure what should I set or what to force.
> 
> Try adding the suggested kernel parameter, "pci=pcie_bus_safe".

Ok, I will try it.

> Unless this is a hot-plug scenario, it is odd the OS was handed
> mismatched PCIe settings. That usually indicates a platform bios issue,
> and the kernel parameter is typically successful at working around it.

This is arm64, no BIOS. Kernel uses native pci-aardvark.c host
controller driver which handles everything related to PCIe.