linux-kernel - Re: [PATCH] Input: synaptics-rmi4 - Do not set reduced reporting mode thresholds are not set by the driver

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Date:   Thu, 12 Mar 2020 13:14:22 +1000
From:   Peter Hutterer <peter.hutterer@...-t.net>
To:     Andrew Duggan <aduggan@...aptics.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Paul Hollinsky <phollinsky@...technik.com>,
        Christopher Heiny <Cheiny@...aptics.com>,
        Lucas Stach <l.stach@...gutronix.de>, kernel@...gutronix.de,
        patchwork-lst@...gutronix.de
Subject: Re: [PATCH] Input: synaptics-rmi4 - Do not set reduced reporting
 mode thresholds are not set by the driver

Hi Andrew,

On Wed, Mar 11, 2020 at 05:55:49PM -0700, Andrew Duggan wrote:
> The previous patch "c5ccf2ad3d33 (Input: synaptics-rmi4 - switch to
> reduced reporting mode)" enabled reduced reporting mode unintentionally
> on some devices, if the firmware was configured with default Delta X/Y
> threshold values. The result unintentionally degrade the performance of
> some touchpads.

could this be the cause of a stuttering cursor on a P50 as well?
A recording in the issue below shows the cursor moving by ~25 units per
event, regardless of the time between those events.
https://gitlab.freedesktop.org/libinput/libinput/issues/448

thanks!

Cheers,
   Peter

> This patch checks to see that the driver is modifying the delta X/Y
> thresholds before modifying the reporting mode.
> 
> Signed-off-by: Andrew Duggan <aduggan@...aptics.com>
> ---
>  drivers/input/rmi4/rmi_f11.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/rmi4/rmi_f11.c b/drivers/input/rmi4/rmi_f11.c
> index 6adea8a3e8fb..ffa39ab153f2 100644
> --- a/drivers/input/rmi4/rmi_f11.c
> +++ b/drivers/input/rmi4/rmi_f11.c
> @@ -1203,8 +1203,8 @@ static int rmi_f11_initialize(struct rmi_function *fn)
>  	 * If distance threshold values are set, switch to reduced reporting
>  	 * mode so they actually get used by the controller.
>  	 */
> -	if (ctrl->ctrl0_11[RMI_F11_DELTA_X_THRESHOLD] ||
> -	    ctrl->ctrl0_11[RMI_F11_DELTA_Y_THRESHOLD]) {
> +	if (sensor->axis_align.delta_x_threshold ||
> +	    sensor->axis_align.delta_y_threshold) {
>  		ctrl->ctrl0_11[0] &= ~RMI_F11_REPORT_MODE_MASK;
>  		ctrl->ctrl0_11[0] |= RMI_F11_REPORT_MODE_REDUCED;
>  	}
> -- 
> 2.20.1
>