linux-kernel - Re: [PATCH v2] pci/aspm: Remove CONFIG_PCIEASPM

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Date:   Sat, 28 Jul 2018 17:16:13 -0700
From:   Sinan Kaya <okaya@...nel.org>
To:     Bjorn Helgaas <helgaas@...nel.org>, Rajat Jain <rajatja@...gle.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Keith Busch <keith.busch@...el.com>,
        Vidya Sagar <vidyas@...dia.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Sinan Kaya <okaya@...eaurora.org>,
        Frederick Lawler <fred@...dlawl.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        mayurkumar.patel@...el.com, rajatxjain@...il.com,
        Richard Hughes <rhughes@...hat.com>,
        Carlos Garnacho <cgarnach@...hat.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Pali Rohar <pali.rohar@...il.com>,
        Takashi Iwai <tiwai@...e.de>,
        Andy Whitcroft <apw@...onical.com>,
        Colin Ian King <colin.king@...onical.com>
Subject: Re: [PATCH v2] pci/aspm: Remove CONFIG_PCIEASPM_DEBUG

On 7/27/2018 1:26 PM, Bjorn Helgaas wrote:
> - A link can lead to a multi-function device, and the spec allows
>      those functions to have different ASPM settings (see PCIe r4.0,
>      sec 5.4.1).  With the sysfs files at the upstream end of the link,
>      we have no way to configure those functions individually.

Even though we can set them individually, there is only one PCIe link
for single function as well as multi-function devices.

It would be a user mistake to allow individual PCIe functions with
different ASPM policies. (maybe, we should enforce it if we are not
doing it already).