Re: [PATCH 1/1] input: ff-memless: Allow negative attack / fade ramps

[Kalle Jokiniemi <kalle.jokiniemi@jolla.com>]

Hi,

Please disregard this patch, the math doesn't really change with this. I 
need to dig deeper what really was the issue, as I could see the 
negative ramp not working.

- Kalle

On 27.08.2015 14:03, Kalle Jokiniemi wrote:
> Currently the ff-memless force feedback periodic effects can only
> have rising attack periods and declining fade periods. E.g. setting
> a attack ramp that starts high to lower to normal magnitude, will
> just cause the effect to rumble at high static speed for duration
> of the attack period and then abruptly lower back to normal
> magnitude instead of linearly declining the effect during attack
> phase.
>
> To fix this, a check has been added to see if the envelope_level
> of the attack or fade period is higher than default magnitude or
> vise versa, and then adjusting the difference value calculation
> accordingly.
>
> Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jolla.com>
> ---
>   drivers/input/ff-memless.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/ff-memless.c b/drivers/input/ff-memless.c
> index 0723e0d..487df7e 100644
> --- a/drivers/input/ff-memless.c
> +++ b/drivers/input/ff-memless.c
> @@ -190,7 +190,10 @@ static int apply_envelope(struct ml_effect_state *state, int value,
>   	} else
>   		return value;
>
> -	difference = abs(value) - envelope_level;
> +	if (abs(value) >= envelope_level)
> +		difference = abs(value) - envelope_level;
> +	else
> +		difference = -(envelope_level - abs(value));
>
>   	pr_debug("difference = %d\n", difference);
>   	pr_debug("time_from_level = 0x%x\n", time_from_level);
>