Re: [PATCH 1/2] elantech: Improved protocol support for hardware 2

["Éric Piel" <E.A.B.Piel@tudelft.nl>]

Op 09-05-10 19:08, Henrik Rydberg schreef:
> Éric Piel wrote:
>> Op 08-05-10 19:45, Henrik Rydberg schreef:
>>> Hi Éric,
>>>
>> :
>>> Please run the ./scripts/checkpatch.pl on patches before submitting them, to
>>> remove trivial formatting errors.
>> Ooops, I usually run it... forgot this time, while it would have been
>> very worthy. Thanks for noticing.
>> Here is a version fixed.
> 
> Thanks, comments below.
:
Thanks for the feedback. I'll fix the comments and resend.

>> @@ -467,6 +480,8 @@ static void elantech_set_input_params(struct psmouse
>> *psmouse)
>>  		break;
>>
>>  	case 2:
>> +		__set_bit(BTN_TOOL_QUADTAP, dev->keybit);
>> +		input_set_abs_params(dev, ABS_TOOL_WIDTH, ETP_WMIN_V2, ETP_WMAX_V2,
>> 0, 0);
> 
> Is there an appropriate signal-to-noise ratio for the width? How does the device
> handle fingers going away? Does it send one or several zero-width events?
What do you mean by SNR for the width? The minimal variation which is
significant for an actual change in the width of the finger? On my
hardware it was fairly precise, and a unit was stable as long as I kept
the finger pressed the same way. Actually at some low pressures I could
swear it detects my blood pulse ;-) That said, in all the measures the
values were between 13 and 55, but I put as min and max 0 and 64. I did
this because I'm not sure it's the same with every version of the
hardware (apparently some old versions of the hardware even just report
0 all the time). It sounded more conservative this way. Is that the
right way?

When you leave the last finger, the device sends one message with "0
finger". However, as it is currently working, the driver then just sends
one "BTN_TOUCH 0", but not any change in the ABS_TOOL_WIDTH. According
to the input protocol, should it also sends in this case a
"ABS_TOOL_WIDTH 0"?

Eric
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