linux-kernel - Re: [PATCH 0/3] PCI/ASPM: Fix L1SS issues

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Date:   Tue, 4 Oct 2022 20:28:07 -0700
From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org
Cc:     Vidya Sagar <vidyas@...dia.com>,
        "Saheed O . Bolarinwa" <refactormyself@...il.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rajat Jain <rajatja@...gle.com>,
        "Kenneth R . Crudup" <kenny@...ix.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Abhishek Sahu <abhsahu@...dia.com>,
        Thierry Reding <treding@...dia.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Thota <kthota@...dia.com>,
        Manikanta Maddireddy <mmaddireddy@...dia.com>,
        Vidya Sagar <sagar.tv@...il.com>, sagupta@...dia.com,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH 0/3] PCI/ASPM: Fix L1SS issues



On 10/4/22 7:58 PM, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> This is really late, but I think we have two significant issues with L1SS:
> 
>   1) pcie_aspm_cap_init() reads from the L1SS capability even when it
>   doesn't exist, so it reads PCI_COMMAND and PCI_STATUS instead and treats
>   those as an L1SS Capability value.
> 
>   2) encode_l12_threshold() encodes LTR_L1.2_THRESHOLD as smaller than
>   requested, so ports may enter L1.2 when they should not.
> 
> These patches are intended to fix both issues.

Looks good to me.

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>

> 
> Bjorn Helgaas (3):
>   PCI/ASPM: Factor out L1 PM Substates configuration
>   PCI/ASPM: Ignore L1 PM Substates if device lacks capability
>   PCI/ASPM: Correct LTR_L1.2_THRESHOLD computation
> 
>  drivers/pci/pcie/aspm.c | 155 +++++++++++++++++++++++-----------------
>  1 file changed, 90 insertions(+), 65 deletions(-)
> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer