[PATCH V3 libinput] evdev: remove checks for fake_resolution

[Peter Hutterer]

On Thu, Jun 25, 2015 at 08:06:29AM -0700, spitzak at gmail.com wrote:
> From: Bill Spitzak <bill.spitzak at dreamworks.com>
> 
> (changes from previous version: rounds the guess and changes 0 to 1,
> removed unused variables)
> 
> Instead a default resolution is set if the device does not claim one.
> The selected value is a guess that the trackpad is 67 mm tall and
> that the device units are square.
> 
> This estimate was arrived at by equating the results calculated when
> fake_resolution is on or off and computing the ratio of units to
> resolution and choosing the most popular value (yres = height / 66.666).
> 
> Also fixes an apparent bug in computing motion_dist.scale_coeff, I
> believe the fake value was the reciprocal of the intended value.
> 
> Unfortunately this patch has not been tested as I lack the ability to do so.
> It is unclear to me if the absinfo_x/y->maximum/minimum fields have been
> filled in before evdev_fix_abs_resolution is called, this patch
> assumes that.
> ---
>  src/evdev-mt-touchpad-buttons.c | 59 +++++++++--------------------------------
>  src/evdev-mt-touchpad.c         | 32 +++++-----------------
>  src/evdev.c                     | 16 ++++++++---
>  3 files changed, 31 insertions(+), 76 deletions(-)
> 

[...]

> diff --git a/src/evdev.c b/src/evdev.c
> index cfcdc34..0bd19a4 100644
> --- a/src/evdev.c
> +++ b/src/evdev.c
> @@ -1748,16 +1748,20 @@ evdev_configure_mt_device(struct evdev_device *device)
>  	int num_slots;
>  	int active_slot;
>  	int slot;
> +	int guessed_resolution;
>  
>  	if (!libevdev_has_event_code(evdev, EV_ABS, ABS_MT_POSITION_X) ||
>  	    !libevdev_has_event_code(evdev, EV_ABS, ABS_MT_POSITION_Y))
>  		 return 0;
>  
> +	guessed_resolution =
> +	    (device->abs.absinfo_y->maximum - device->abs.absinfo_y->minimum + 1 + 33) / 67;
> +	if (guessed_resolution < 1) guessed_resolution = 1;
>  	if (evdev_fix_abs_resolution(device,
>  				     ABS_MT_POSITION_X,
>  				     ABS_MT_POSITION_Y,
> -				     EVDEV_FAKE_RESOLUTION,
> -				     EVDEV_FAKE_RESOLUTION))
> +				     guessed_resolution,
> +				     guessed_resolution))
>  		device->abs.fake_resolution = 1;
>  
>  	device->abs.absinfo_x = libevdev_get_abs_info(evdev, ABS_MT_POSITION_X);


sigh. I understand that you may not have a device to trigger certain
conditions but that's exactly why we have a test suite. you didn't even run
that, otherwise you'd have noticed this segfaults immediately on every
touchpad - you're using absinfo 5 lines before it is assigned.

Cheers,
   Peter