performance of USB mouse initialization on startup
daniel at fooishbar.org
Thu Jun 10 04:04:34 PDT 2010
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
> 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
> The Linux USB mouse driver for /dev/input/mice emulates the IntelliMouse
> and IntelliMouse Explorer (a.k.a. "ImPS/2" and "ExplorerPS/2" in
> 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
> somebody, somewhere still cares about. My first cut a fix that
> 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.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Size: 198 bytes
Desc: Digital signature
More information about the xorg-devel