linux-kernel - Re: [PATCH 4/4] PCI/ASPM: Don't select CONFIG

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Date:   Mon, 1 Jun 2020 11:31:34 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     linux-pci@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Christoph Hellwig <hch@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH 4/4] PCI/ASPM: Don't select CONFIG_PCIEASPM by default

On Tue, Apr 14, 2020 at 07:12:44PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> PCIe Active State Power Management (ASPM) is optional and there's no need
> for it to be selected by default.
> 
> Remove the "default y" for CONFIG_PCIEASPM.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Heiner Kallweit <hkallweit1@...il.com>

I dropped this patch for now.

Without CONFIG_PCIEASPM, Linux doesn't request control of *any*
features via _OSC (see ACPI_PCIE_REQ_SUPPORT), which means we can't
use PCIe PME to resume from runtime suspend.

https://bugzilla.redhat.com/show_bug.cgi?id=638912
https://lore.kernel.org/r/2e1ee784-7493-284b-96f9-96b2e0c4b817@gmail.com

> ---
>  drivers/pci/pcie/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
> index 9cd31331aee9..5b7b460a8a98 100644
> --- a/drivers/pci/pcie/Kconfig
> +++ b/drivers/pci/pcie/Kconfig
> @@ -62,7 +62,6 @@ config PCIE_ECRC
>  #
>  config PCIEASPM
>  	bool "PCI Express ASPM control" if EXPERT
> -	default y
>  	help
>  	  This enables OS control over PCI Express ASPM (Active State
>  	  Power Management) and Clock Power Management. ASPM supports
> -- 
> 2.26.0.110.g2183baf09c-goog
>