linux-kernel - Re: Re [patch 2/3] fastboot: turn the USB hostcontroller initcalls into async initcalls

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Message-ID: <20080719083942.2daa2959@infradead.org>
Date:	Sat, 19 Jul 2008 08:39:42 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Kernel development list <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>
Subject: Re: Re  [patch 2/3] fastboot: turn the USB hostcontroller initcalls
 into async initcalls

On Sat, 19 Jul 2008 11:25:29 -0400 (EDT)
Alan Stern <stern@...land.harvard.edu> wrote:

> On 18 July, 2008, Arjan van de Ven wrote:
> 
> > From: Arjan van de Ven <arjan@...ux.intel.com>
> > Subject: [PATCH] fastboot: turn the USB hostcontroller initcalls
> > into async initcalls
> > 
> > the USB host controller init calls take a long time, mostly due to a
> > "minimally 100 msec" delay *per port* during initialization.
> > These are prime candidates for going in parallel to everything else.
> > 
> > The USB device ordering is not affected by this due to the
> > serialized-within-eachother property of async initcalls.
> 
> 
> Where is this "minimally 100 msec" per-port delay you refer to?  
> Offhand I can't recall any such delays in the init routines.
> 

it's here (in drivers/usb/core/hub.c::hub_power_on):

                                "non-switchable hub\n");
        for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++)
                set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);

        /* Wait at least 100 msec for power to become stable */
        msleep(max(pgood_delay, (unsigned) 100));
}

at least my eeepc901 hits that like 6 or 7 times
(because if I shorten the 100 the boot goes a ton faster.. but that's
obviously just a bad hack)
-- 
If you want to reach me at my work email, use arjan@...ux.intel.com
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