linux-kernel - Re: How to enable auto-suspend by default

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Message-ID: <56726c3591feb0a61dd2bf8ffa5dc218af46cbab.camel@hadess.net>
Date:   Tue, 24 Nov 2020 16:53:00 +0100
From:   Bastien Nocera <hadess@...ess.net>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     "Limonciello, Mario" <Mario.Limonciello@...l.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>
Subject: Re: How to enable auto-suspend by default

On Tue, 2020-11-24 at 14:37 +0200, Mathias Nyman wrote:
> <snip>
> I don't think we are ready to enable runtime pm as default for all
> Intel xHCI controllers.
> The risk of xHCI not waking up when user plugs a mouse/keyboard,
> making the system unusable
> just seems too high compared to the powersaving benefit.
> 
> The powersaving benefit from autosuspending the TCSS xHCI is a lot
> better, and we, (Mika mostly)
> has been able to verify they work.
> 
> So I propose we for now continue adding TCSS xHCI controllers to the
> allowlist in kernel.
> For others I think a userspace allow/denylist makes sense.
> 
> Long term goal would be default allow for all, with short denylist in
> kernel.

Is there any way to preemptively enable autosuspend for all the _TCSS_
xHCI controllers?

This was the problem the original post tried to tease out, whether it
would be easier/better to enable autosuspend by default, and not enable
it on systems where it breaks something, rather than default to sucking
battery until somebody notices that a device ID got missed.