[PATCH synaptics] Increase the default acceleration factor.

[Magnus Kessler]

On Thursday 19 August 2010 06:14:08 Peter Hutterer wrote:
> With 4e0e53fcba6fd99d458df1905d055d63360155c0 the driver got it's own
> acceleration mechanism. This slowed down the pointer movement a lot,
> especially on ALPS touchpads. Increase the default acceleration factor to
> accommodate for this.
> 
> The number itself is chosen through guesswork and informal tests on one
> Synaptics and one ALPS pad.
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  src/synaptics.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/src/synaptics.c b/src/synaptics.c
> index 3344d75..9d0bf14 100644
> --- a/src/synaptics.c
> +++ b/src/synaptics.c
> @@ -455,7 +455,7 @@ static void set_default_parameters(LocalDevicePtr
> local) tapMove = diag * .044;
>      edgeMotionMinSpeed = 1;
>      edgeMotionMaxSpeed = diag * .080;
> -    accelFactor = 50.0 / diag;
> +    accelFactor = 200.0 / diag; /* trial-and-error */
> 
>      range = priv->maxp - priv->minp;

Tested on a Lenovo T500 (Synaptics Touchpad, model: 1, fw: 7.0, id: 0x1c0b1, 
caps: 0xd04791/0xb00000/0x20000). Works well for me.

There seems to be an awful amount of ad-hoc magic factors in that part of the 
code though. And comments like "Again, based on typical x/y range and 
defaults". Does anyone know of a way to express the factors in a more rational 
way?

For this patch, though:

Tested-by: Magnus Kessler <Magnus.Kessler at gmx.net>
Reviewed-by: Magnus Kessler <Magnus.Kessler at gmx.net>