From: Greg KH <gregkh@linuxfoundation.org>
To: "Limonciello, Mario" <Mario.Limonciello@dell.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Bastien Nocera <hadess@hadess.net>,
Linux PM <linux-pm@vger.kernel.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
Mathias Nyman <mathias.nyman@linux.intel.com>
Subject: Re: How to enable auto-suspend by default
Date: Wed, 11 Nov 2020 17:32:22 +0100 [thread overview]
Message-ID: <X6wSFojYLvwGhY/g@kroah.com> (raw)
In-Reply-To: <DM6PR19MB26366008D59FC94D384A1E3BFAE80@DM6PR19MB2636.namprd19.prod.outlook.com>
On Wed, Nov 11, 2020 at 04:03:30PM +0000, Limonciello, Mario wrote:
> > >> Given we're effectively ending up with the combination of runtime PM turned
> > >> on by udev rules, do we need something like this for that ID:
> > >>
> > >>
> > https://github.com/torvalds/linux/commit/6a7c533d4a1854f54901a065d8c672e890400
> > d8a
> > >>
> > >> @Mika Westerberg should 8086:a0ed be quirked like the TCSS xHCI too?
> > >
> > > I think this one is the TGL PCH xHCI. The quirk currently for xHCI
> > > controllers that are part of the TCSS (Type-C SubSystem) where it is
> > > important to put all devices into low power mode whenever possible,
> > > otherwise it keeps the whole block on.
> >
> > Note that there are currently some IDs missing from the xHCIs which
> > are part of the TCSS too. At least the id for the xHCI in the thunderbolt
> > controller on the Lenovo T14 gen 1 is missing. I started a discussion
> > about extending the kernel quirk list for this vs switching to hwdb
> > a while a go:
> >
> > https://lore.kernel.org/linux-usb/b8b21ba3-0a8a-ff54-5e12-
> > cf8960651086@redhat.com/
> >
> > The conclusion back then was to switch to hwdb, but I never got around to
> > this.
>
> I guess the problem I see with switching to a hwdb for this type of thing is
> that if there is a "bug" in your kernel driver around autosuspend you will
> then be potentially causing it to occur more regularly on a kernel that didn't
> necessarily pick up the fix but does have the newer hwdb.
>
> I don't know how common that will really be though.
>
> Since Mika mentioned the really light userspace scenario, what about shipping
> the hwdb "with" the kernel in tree? This could allow evicting all these quirk
> scenarios from the kernel at the same time as switching to a hwdb and also cover
> the problem I suggested might happen with a bug in older kernel and newer userspace.
We took things out of the kernel to put it in hwdb years ago as it was
easier for people to update a "text file" than it was their kernel
image. I don't think you want to go backwards here :)
thanks,
greg k-h
next prev parent reply other threads:[~2020-11-11 16:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-10 10:57 How to enable auto-suspend by default Bastien Nocera
2020-11-10 11:34 ` Greg KH
2020-11-10 16:02 ` Limonciello, Mario
2020-11-10 17:18 ` Greg KH
2020-11-10 17:45 ` Limonciello, Mario
2020-11-10 18:00 ` Greg KH
2020-11-10 18:08 ` Limonciello, Mario
2020-11-10 19:55 ` Theodore Y. Ts'o
2020-11-10 20:45 ` Limonciello, Mario
2020-11-10 17:25 ` Mika Westerberg
2020-11-11 11:27 ` Hans de Goede
2020-11-11 14:31 ` Mika Westerberg
2020-11-23 13:54 ` Hans de Goede
2020-11-23 14:01 ` Mika Westerberg
2020-11-24 12:37 ` Mathias Nyman
2020-11-24 12:38 ` Hans de Goede
2020-11-24 15:53 ` Bastien Nocera
2020-11-11 16:03 ` Limonciello, Mario
2020-11-11 16:32 ` Greg KH [this message]
2020-11-24 16:02 ` Bastien Nocera
2020-11-24 16:35 ` Greg KH
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