performance of USB mouse initialization on startup

[B.S., Shashi Shekar]

> -----Original Message-----
> From: xorg-devel-bounces+shashi.shekar=ti.com at lists.x.org 
> [mailto:xorg-devel-bounces+shashi.shekar=ti.com at lists.x.org] 
> On Behalf Of Tiago Vignatti
> Sent: Thursday, June 10, 2010 4:38 PM
> To: ext Daniel Stone
> Cc: xorg-devel at lists.x.org; Richard Barnette
> Subject: Re: performance of USB mouse initialization on startup
> 
> On Thu, Jun 10, 2010 at 01:04:34PM +0200, ext Daniel Stone wrote:
> > On Wed, Jun 09, 2010 at 12:26:34PM -0700, Richard Barnette wrote:
> > > "And for my next trick..."
> > > 
> > > Initialization for PS/2 compatible mice uses a number of 
> explicit calls
> > > to usleep().  The code mostly lives in src/pnp.c, under
> > > xorg/driver/xf86-input-mouse.
> > > 
> > > The pattern of sleep calls is sufficiently systematic to suggest
> > > that they're specifically prescribed by a hardware spec.  Alas,
> > > hardware specs for the PS/2 mouse, MS IntelliMouse, IntelliMouse
> > > Explorer, etc. aren't readily available online to confirm 
> this.  The
> > > best reference I've found is
> > > http://www.computer-engineering.org/ps2mouse/.
> > > 
> > > The Linux USB mouse driver for /dev/input/mice emulates 
> the IntelliMouse
> > > and IntelliMouse Explorer (a.k.a. "ImPS/2" and "ExplorerPS/2" in
> > > src/mouse.c)
> > > in software.  AFAICT, the usleep() calls are unneeded for 
> USB mice on
> > > Linux.  (I've tested and confirmed that deleting the calls has no
> > > immediately visible impact on Chromium OS).
> > > 
> > > The usleep() calls during mouse initialization total up 
> to 230 ms on my
> > > test configuration.  That's big enough to cry out for a 
> fix.  However,
> > > I assume that merely deleting the calls will break a 
> hardware config
> > > that
> > > somebody, somewhere still cares about.  My first cut a fix that
> > > preserves
> > > compatibility would be to add a new protocol (e.g. 
> "LinuxUSB") that
> > > tracks either "ImPS/2" or "ExplorerPS/2", but omits 
> unnecessary delays.
> > > 
> > > Any advice on this?
> > 
> > Don't use xf86-input-mouse, or xf86-input-keyboard! Really, 
> don't.  Use
> > evdev.  It's less shit, starts up quicker, supports a lot 
> more stuff, is
> > actually maintained, has no unnecessary usleeps, and 
> basically you'll
> > just hate your life less.
> 
> Does it makes sense to set a trap on autoconf to disables 
> Linux on those
> drivers then?
> 
That's better. 2 less drivers for people in Linux world to worry about!

-Shashi