linux-kernel - Re: [External] : [PATCH v2 1/3] PCI: Always lift 2.5GT/s restriction in PCIe failed link retraining

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Message-ID: <3f3e55c2-6670-4e63-9418-b2e5c8743347@oracle.com>
Date: Thu, 5 Feb 2026 16:30:45 +0530
From: ALOK TIWARI <alok.a.tiwari@...cle.com>
To: "Maciej W. Rozycki" <macro@...am.me.uk>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Matthew W Carlis <mattc@...estorage.com>
Cc: ashishk@...estorage.com, msaggi@...estorage.com, sconnor@...estorage.com,
        Lukas Wunner <lukas@...ner.de>,
        Ilpo Järvinen
 <ilpo.jarvinen@...ux.intel.com>,
        Jiwei <jiwei.sun.bj@...com>, guojinhui.liam@...edance.com,
        ahuang12@...ovo.com, sunjw10@...ovo.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [External] : [PATCH v2 1/3] PCI: Always lift 2.5GT/s restriction
 in PCIe failed link retraining



On 12/9/2025 12:54 AM, Maciej W. Rozycki wrote:
> Discard Vendor:Device ID matching in the PCIe failed link retraining
> quirk and ignore the link status for the removal of the 2.5GT/s speed
> clamp, whether applied by the quirk itself or the firmware earlier on.
> Revert to the original target link speed if this final link retraining
> has failed.
> 
> This is so that link training noise in hot-plug scenarios does not make
> a link remain clamped to the 2.5GT/s speed where an event race has led
> the quirk to apply the speed clamp for one device, only to leave it in
> place for a subsequent device to be plugged in.
> 
> Refer to the Link Capabilities register directly for the maximum link
> speed determination so as to streamline backporting.
> 
> Fixes: a89c82249c37 ("PCI: Work around PCIe link training failures")
> Tested-by: Alok Tiwari<alok.a.tiwari@...cle.com>
> Signed-off-by: Maciej W. Rozycki<macro@...am.me.uk>
> Cc:<stable@...r.kernel.org> # v6.5+

Tested-by: Alok Tiwari <alok.a.tiwari@...cle.com>

Tested with LTS 6.18.

Thanks,
Alok