linux-kernel - Re: [PATCH 1/2] amd_nb: Add PCI ID for family 19h model 78h

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Date:   Thu, 27 Apr 2023 11:46:51 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        Sanket Goswami <Sanket.Goswami@....com>,
        Richard gong <richard.gong@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: Re: [PATCH 1/2] amd_nb: Add PCI ID for family 19h model 78h

On Thu, Apr 27, 2023 at 12:33:36AM -0500, Mario Limonciello wrote:
> s2idle previously worked on this system, but it regressed in kernel
> 6.4 due to commit 310e782a99c7 ("platform/x86/amd: pmc: Utilize SMN
> index 0 for driver probe").
> 
> The reason for the regression is that before this commit the SMN
> communication was hardcoded, but after amd_smn_read() is used which
> relies upon the misc PCI ID used by DF function 3 being included in
> a table.  The ID was missing for model 78h, so this meant that the
> amd_smn_read() wouldn't work.
> 
> Add the missing ID into amd_nb, restoring s2idle on this system.

Is there a long-term solution for this that will not require adding
new IDs every time new hardware comes out?

drivers/platform/x86/amd/pmc.c already matches ACPI IDs; maybe there's
some way for the platform to provide the information you need via
ACPI or something?

Bjorn