Re: [PATCH] Input: synaptics-rmi4 - switch to reduced reporting mode

[Andrew Duggan <aduggan@synaptics.com>]

Hi Dmitry,

On 1/26/20 6:24 PM, Dmitry Torokhov wrote:
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>
> On Mon, Jan 20, 2020 at 12:16:28PM +0100, Lucas Stach wrote:
>> When the distance thresholds are set the controller must be in reduced
>> reporting mode for them to have any effect on the interrupt generation.
>> This has a potentially large impact on the number of events the host
>> needs to process.
>>
>> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
>> ---
>> I'm not sure if we want a separate DT property to allow the use of
>> reduced reporting mode, as this change might lead to problems for
>> controllers with unreasonably large threshold values. I'm not sure if
>> any controller with bogus threshold values exist in the wild.
>> ---
> Andrew, any feedback on this patch?
>
> Thanks!

The RMI4 spec does say that delta X/Y thresholds are only used in 
reduced reporting mode, so this patch is needed for the threshold values 
to have an effect.

Reviewed-by: Andrew Duggan <aduggan@synaptics.com>

Because reduced reporting mode is so dependent on these thresholds, my 
opinion is that it is better not to add a separate DT property, but to 
instead control reduced reporting mode through the setting of these 
thresholds. My guess is that the if reduced reporting is not enabled in 
the firmware by default, then the thresholds may not be valid. Setting 
the thresholds to 0 will essentially disable reduced reporting mode. So 
that would be how a user could disable reduced reporting mode without a 
separate DT property. Chris, do you have an opinion on this? Anything I 
overlooked?

Andrew

>>   drivers/input/rmi4/rmi_f11.c | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/input/rmi4/rmi_f11.c b/drivers/input/rmi4/rmi_f11.c
>> index bbf9ae9f3f0c..6adea8a3e8fb 100644
>> --- a/drivers/input/rmi4/rmi_f11.c
>> +++ b/drivers/input/rmi4/rmi_f11.c
>> @@ -412,6 +412,10 @@ struct f11_2d_sensor_queries {
>>
>>   /* Defs for Ctrl0. */
>>   #define RMI_F11_REPORT_MODE_MASK        0x07
>> +#define RMI_F11_REPORT_MODE_CONTINUOUS  (0 << 0)
>> +#define RMI_F11_REPORT_MODE_REDUCED     (1 << 0)
>> +#define RMI_F11_REPORT_MODE_FS_CHANGE   (2 << 0)
>> +#define RMI_F11_REPORT_MODE_FP_CHANGE   (3 << 0)
>>   #define RMI_F11_ABS_POS_FILT            (1 << 3)
>>   #define RMI_F11_REL_POS_FILT            (1 << 4)
>>   #define RMI_F11_REL_BALLISTICS          (1 << 5)
>> @@ -1195,6 +1199,16 @@ static int rmi_f11_initialize(struct rmi_function *fn)
>>                ctrl->ctrl0_11[RMI_F11_DELTA_Y_THRESHOLD] =
>>                        sensor->axis_align.delta_y_threshold;
>>
>> +     /*
>> +      * 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]) {
>> +             ctrl->ctrl0_11[0] &= ~RMI_F11_REPORT_MODE_MASK;
>> +             ctrl->ctrl0_11[0] |= RMI_F11_REPORT_MODE_REDUCED;
>> +     }
>> +
>>        if (f11->sens_query.has_dribble) {
>>                switch (sensor->dribble) {
>>                case RMI_REG_STATE_OFF:
>> --
>> 2.20.1
>>
> --
> Dmitry