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From: Mark Lord <lkml@rtr.ca>
To: Andrew Morton <akpm@osdl.org>
Cc: David Liontooth <liontooth@cogweb.net>,
	linux-kernel@vger.kernel.org,
	linux-usb-devel@lists.sourceforge.net,
	Alan Stern <stern@rowland.harvard.edu>
Subject: Re: USB devices fail unnecessarily on unpowered hubs
Date: Thu, 01 Jun 2006 13:34:46 -0400	[thread overview]
Message-ID: <447F2536.9030904@rtr.ca> (raw)
In-Reply-To: <20060601030140.172239b0.akpm@osdl.org>

Andrew Morton wrote:
> On Thu, 01 Jun 2006 02:18:20 -0700
> ..
>> This is generating a lot of grief and appears to be unnecessarily
>> strict. Common USB sticks with a MaxPower value just above 100mA, for
>> instance, typically work fine on unpowered hubs supplying 100mA.
>>
>> Is a more user-friendly solution possible? Could the shortfall
>> information be passed to udev, which would allow rules to be written per
>> device?
..
> Yes, it sounds like we're being non-real-worldly here.  This change
> apparently broke things.  Did it actually fix anything as well?

I think a far more sensible approach would be to just ensure that the
total current draw for the (unpowered) hub and all connected devices,
stays below the 500mA allowed.  So a 200mA device could coexist with
a 100mA device on a hub which itself steals 100mA.

Cheers

  parent reply	other threads:[~2006-06-01 17:34 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-06-01  9:18 USB devices fail unnecessarily on unpowered hubs David Liontooth
2006-05-30 20:01 ` Pavel Machek
2006-06-03  9:29   ` Oliver Neukum
2006-06-05 14:32     ` [linux-usb-devel] " David Brownell
2006-06-06  7:43       ` Oliver Neukum
2006-06-08  7:01         ` Pavel Machek
2006-06-08  8:34       ` [PATCH] limit power budget on spitz Pavel Machek
2006-06-08  8:50         ` Richard Purdie
2006-06-08  9:02           ` Pavel Machek
2006-06-08  9:22             ` Richard Purdie
2006-06-08 17:09               ` Russell King
2006-06-08 18:26                 ` David Brownell
2006-06-08 20:06                   ` Richard Purdie
2006-06-08 20:38                     ` [linux-usb-devel] " David Brownell
2006-06-08 21:22                       ` Richard Purdie
2006-06-08 21:40                         ` David Brownell
2006-06-08 21:49                           ` Richard Purdie
2006-06-08 23:44                             ` David Brownell
2006-06-09  1:25                               ` Nicolas Pitre
2006-06-09  2:03                                 ` David Brownell
2006-06-09  2:34                                   ` Nicolas Pitre
2006-06-01 10:01 ` USB devices fail unnecessarily on unpowered hubs Andrew Morton
2006-06-01 11:42   ` Daniel Drake
2006-06-01 14:58   ` Alan Stern
2006-06-01 15:09     ` linux-os (Dick Johnson)
2006-06-01 15:23       ` Lennart Sorensen
2006-06-01 21:39         ` Dagfinn Ilmari Mannsåker
2006-06-01 15:53       ` Oliver Neukum
2006-06-01 17:24         ` linux-os (Dick Johnson)
2006-06-01 16:57       ` Alan Stern
2006-06-01 16:43     ` [linux-usb-devel] " Greg KH
2006-06-02  0:03       ` David Liontooth
2006-06-02  1:53         ` [linux-usb-devel] " David Brownell
2006-06-02  7:12         ` Oliver Neukum
2006-06-02 15:11         ` Alan Stern
2006-06-02 19:49           ` David Liontooth
2006-06-01 16:59     ` Andrew Morton
2006-06-01 17:08       ` Alan Stern
2006-06-01 17:34   ` Mark Lord [this message]
2006-06-01 17:47     ` Alan Stern
     [not found] <6iWP5-2gj-71@gated-at.bofh.it>
     [not found] ` <6iX82-2UJ-3@gated-at.bofh.it>
2006-06-01 23:35   ` Robert Hancock
2006-06-01 23:46     ` Randy.Dunlap
     [not found] <6iYGP-5hv-3@gated-at.bofh.it>
     [not found] ` <6iYQx-5Jc-7@gated-at.bofh.it>
2006-06-01 23:37   ` Robert Hancock
  -- strict thread matches above, loose matches on Subject: below --
2006-06-05 11:07 Lee Dowling
     [not found] <6kl8h-1Uf-15@gated-at.bofh.it>
2006-06-07  0:51 ` Robert Hancock

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