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Subject: Re: [PATCH] r8169: add enable_aspm parameter
To:     AceLan Kao <acelan.kao@canonical.com>,
        Realtek linux nic maintainers <nic_swsd@realtek.com>,
        "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20190708063751.16234-1-acelan.kao@canonical.com>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <53f82481-ed41-abc5-2e4e-ac1026617219@gmail.com>
Date:   Mon, 8 Jul 2019 20:27:25 +0200
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On 08.07.2019 08:37, AceLan Kao wrote:
> We have many commits in the driver which enable and then disable ASPM
> function over and over again.
>    commit b75bb8a5b755 ("r8169: disable ASPM again")
>    commit 0866cd15029b ("r8169: enable ASPM on RTL8106E")
>    commit 94235460f9ea ("r8169: Align ASPM/CLKREQ setting function with vendor driver")
>    commit aa1e7d2c31ef ("r8169: enable ASPM on RTL8168E-VL")
>    commit f37658da21aa ("r8169: align ASPM entry latency setting with vendor driver")
>    commit a99790bf5c7f ("r8169: Reinstate ASPM Support")
>    commit 671646c151d4 ("r8169: Don't disable ASPM in the driver")
>    commit 4521e1a94279 ("Revert "r8169: enable internal ASPM and clock request settings".")
>    commit d64ec841517a ("r8169: enable internal ASPM and clock request settings")
> 
> This function is very important for production, and if we can't come out
> a solution to make both happy, I'd suggest we add a parameter in the
> driver to toggle it.
> 
The usage of a module parameter to control ASPM is discouraged.
There have been more such attempts in the past that have been declined.

Pending with the PCI maintainers is a series adding ASPM control
via sysfs, see here: https://www.spinics.net/lists/linux-pci/msg83228.html

Also more details than just stating "it's important for production"
would have been appreciated in the commit message, e.g. which
power-savings you can achieve with ASPM on which systems.