From: Oliver Neukum <oliver@neukum.org>
To: Greg KH <greg@kroah.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>,
Sarah Sharp <sarah.a.sharp@linux.intel.com>,
linux-usb@vger.kernel.org, linux-media@vger.kernel.org,
linux-kernel@vger.kernel.org, libusb-devel@lists.sourceforge.net,
Alexander Graf <agraf@suse.de>, Gerd Hoffmann <kraxel@redhat.com>,
hector@marcansoft.com, Jan Kiszka <jan.kiszka@siemens.com>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
pbonzini@redhat.com, Anthony Liguori <aliguori@us.ibm.com>,
Jes Sorensen <Jes.Sorensen@redhat.com>,
Alan Stern <stern@rowland.harvard.edu>,
Felipe Balbi <balbi@ti.com>, Clemens Ladisch <clemens@ladisch.de>,
Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.de>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Hans de Goede <hdegoede@redhat.com>,
Theodore Kilgore <kilgota@banach.math.auburn.edu>,
Adam Baker <linux@baker-net.org.uk>
Subject: Re: USB mini-summit at LinuxCon Vancouver
Date: Fri, 5 Aug 2011 08:57:52 +0200 [thread overview]
Message-ID: <201108050857.52204.oliver@neukum.org> (raw)
In-Reply-To: <20110804225603.GA2557@kroah.com>
Am Freitag, 5. August 2011, 00:56:03 schrieb Greg KH:
> On Thu, Aug 04, 2011 at 07:21:47PM -0300, Mauro Carvalho Chehab wrote:
> > I know that this problem were somewhat solved for 3G modems, with the usage
> > of the userspace problem usb_modeswitch, and with some quirks for the USB
> > storage driver, but I'm not sure if such tricks will scale forever, as more
> > functions are seen on some USB devices.
>
> Well, no matter how it "scales" it needs to be done in userspace, like
> usb_modeswitch does. We made that decision a while ago, and it is
> working out very well. I see no reason why you can't do it in userspace
> as well as that is the easiest place to control this type of thing.
>
> I thought we had a long discussion about this topic a while ago and came
> to this very conclusion. Or am I mistaken?
Circumstances change. We want to keep the stuff in user space as much and
as long as we can. However user space has limitations:
- it has by necessity a race between resumption and access by others
- it cannot resume anything we run a (rw) filesystem over.
Furthermore, today PM actions that lead to a loss of mode are initiated
by user space. If we ever want to oportunistically suspend a system
we also need to restore mode from inside the kernel.
We could avoid all that trouble, if we persuaded vendors to use plain
USB configurations for those purposes.
Regards
Oliver
next prev parent reply other threads:[~2011-08-05 6:55 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-10 0:21 USB mini-summit at LinuxCon Vancouver Sarah Sharp
2011-06-10 3:18 ` Greg KH
2011-06-10 6:59 ` Gerd Hoffmann
2011-06-10 19:48 ` Sarah Sharp
2011-06-10 20:50 ` Greg KH
2011-06-13 10:44 ` Alexander Graf
2011-06-13 10:44 ` Alexander Graf
2011-06-13 16:29 ` Greg KH
2011-06-13 16:29 ` Greg KH
2011-06-13 17:11 ` Alexander Graf
2011-06-13 17:11 ` Alexander Graf
2011-06-10 7:19 ` Hans de Goede
2011-06-10 7:55 ` Improving kernel -> userspace (usbfs) usb device hand off Hans de Goede
2011-06-10 8:22 ` Felipe Balbi
2011-06-10 8:36 ` Hans de Goede
2011-06-10 8:42 ` Felipe Balbi
2011-06-10 12:19 ` Hans de Goede
2011-06-10 12:28 ` Felipe Balbi
2011-06-10 14:48 ` Alan Stern
2011-06-10 15:07 ` Mauro Carvalho Chehab
2011-06-10 15:21 ` Alan Stern
2011-06-11 9:15 ` Hans de Goede
2011-06-11 16:19 ` Theodore Kilgore
2011-06-12 11:43 ` Hans de Goede
2011-06-12 21:20 ` Theodore Kilgore
2011-06-13 2:03 ` Xiaofan Chen
2011-06-13 2:27 ` [Libusb-devel] " Michael Bender
2011-06-11 16:57 ` Alan Stern
2011-06-10 18:16 ` Theodore Kilgore
2011-06-10 18:34 ` Felipe Balbi
2011-06-10 21:18 ` Alan Stern
2011-06-10 21:46 ` Felipe Balbi
2011-06-10 22:46 ` Theodore Kilgore
2011-06-10 22:43 ` Theodore Kilgore
2011-06-11 1:30 ` Xiaofan Chen
2011-06-11 4:17 ` Theodore Kilgore
2011-06-13 9:05 ` Felipe Balbi
2011-06-13 13:06 ` Mauro Carvalho Chehab
2011-06-13 13:12 ` Felipe Balbi
2011-08-04 22:21 ` USB mini-summit at LinuxCon Vancouver Mauro Carvalho Chehab
2011-08-04 22:56 ` Greg KH
[not found] ` <CAA6KcBBZv7bvVxvEWOYL83igpNZHyzh=bcGxh6Dr5aKsvJK5Cg@mail.gmail.com>
2011-08-05 0:33 ` Mauro Carvalho Chehab
2011-08-05 2:56 ` Theodore Kilgore
2011-08-05 6:57 ` Oliver Neukum [this message]
2011-08-05 17:38 ` Theodore Kilgore
2011-08-05 7:45 ` Hans de Goede
2011-08-05 7:59 ` USB mini-summit at LinuxCon Vancouveroliver Oliver Neukum
2011-08-05 8:18 ` Hans de Goede
2011-08-05 13:07 ` USB mini-summit at LinuxCon Vancouver Mauro Carvalho Chehab
2011-08-08 17:58 ` Sarah Sharp
2011-08-08 18:23 ` Theodore Kilgore
2011-08-08 18:32 ` Sarah Sharp
2011-08-08 19:37 ` Mauro Carvalho Chehab
2011-08-09 7:52 ` Hans de Goede
2011-08-09 14:19 ` Alan Stern
2011-08-09 15:03 ` Marko Ristola
2011-08-09 19:57 ` Hans de Goede
2011-08-09 20:31 ` Adam Baker
2011-08-09 20:57 ` Hans de Goede
2011-08-10 2:05 ` Xiaofan Chen
2011-08-10 23:04 ` Adam Baker
2011-08-11 8:14 ` Hans de Goede
2011-08-09 23:05 ` Theodore Kilgore
2011-08-10 14:19 ` Alan Stern
2011-08-10 15:03 ` Theodore Kilgore
2011-08-10 16:09 ` Alan Stern
2011-08-10 18:33 ` Theodore Kilgore
2011-08-10 19:39 ` Hans Verkuil
2011-08-10 19:43 ` Greg KH
2011-08-10 20:34 ` Theodore Kilgore
2011-08-10 20:14 ` Mauro Carvalho Chehab
2011-08-10 20:39 ` Theodore Kilgore
2011-08-11 8:57 ` Jean-Francois Moine
2011-08-11 11:19 ` Mauro Carvalho Chehab
2011-08-11 8:14 ` Hans de Goede
2011-08-11 14:56 ` Alan Stern
2011-08-11 15:13 ` Mauro Carvalho Chehab
2011-08-11 15:25 ` Alan Cox
2011-08-11 15:49 ` Alan Stern
2011-08-11 20:01 ` Theodore Kilgore
2011-08-11 20:32 ` Mauro Carvalho Chehab
2011-08-11 23:13 ` Theodore Kilgore
2011-08-12 7:16 ` Hans de Goede
2011-08-12 10:11 ` Alan Cox
2011-08-12 1:07 ` Alan Stern
2011-08-12 2:38 ` Theodore Kilgore
2011-08-11 15:44 ` Alan Stern
2011-08-12 7:26 ` Hans de Goede
2011-08-12 15:36 ` Alan Stern
2011-08-09 17:10 ` Sarah Sharp
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