Re: [PATCH 2/6] Input: elantech - use firmware provided x, y ranges

Éric Piel
2011-08-19T12:19:16Z

Op 19-08-11 11:47, JJ Ding schreef:
> Hi Dmitry,
>
> Sorry for late reply. I missed this one somehow.
>
> On Thu, 18 Aug 2011 00:47:56 -0700, Dmitry Torokhov<dmitry.torokhov@gmail.com> wrote:
>> On Thu, Aug 18, 2011 at 09:57:05AM +0800, JJ Ding wrote:
>>> +
>>> + i = (etd->fw_version> 0x020800&&
>>> + etd->fw_version< 0x020900) ? 1 : 2;
>>> + *x_max = (etd->capabilities[1] - i) * 64;
>>> + *y_max = (etd->capabilities[2] - i) * 64;
>>> + *y_2ft_max = (*y_max - i) * 64 / 4;
>>
>> Hmm, we should have the same range for ST and MT data and scale MT data
>> if it has lower resolution to match ST.
> So I should just remove y_2ft_max and those ETP_2FT_XXXX in elantech.h,
> and do the scale in elantech_report_absolute_v2?
Humm, yes, I think what Dmitry wants is that both ABS_MT_POSITION_Y and
ABS_Y have the same min and max, and the scaling is done when reading
the data. However, it seems this already what is being tried to be done,
excepted that I mess it up in the latest patch set I sent. I just
noticed it now, sorry :-S

You can see in elantech_report_absolute_v2() in case of 2 fingers:
The part for updating ABS_X, ABS_Y is correct:
input_report_abs(dev, ABS_X, x1 << 2);
input_report_abs(dev, ABS_Y, y1 << 2);

But I forgot to do the same for MT:
elantech_report_semi_mt_data(dev, fingers, x1, y1, x2, y2);
That should be:
elantech_report_semi_mt_data(dev, fingers, x1 << 2, y1 << 2, x2 << 2,
y2 << 2);

Or, even more clean, just move the shift directly into the computation,
like:
y1 = etd->y_max - ((((packet[0] & 0x20) << 3) | packet[2]) << 2);

In such case you can drop completely y_2ft_max, and move the
input_report_abs() outside of the switch.

In addition, I have a couple of more remarks on this patch:
> + *x_max = (etd->capabilities[1] - i) * 64;
> + *y_max = (etd->capabilities[2] - i) * 64;
> + *y_2ft_max = (*y_max - i) * 64 / 4;
This last line is probably wrong as I think it should be:
*y_2ft_max = *y_max / 4;

But if you drop y_2ft_max, that shouldn't matter anymore!
> + case 1:
> + *x_min = ETP_XMIN_V1;
> + *y_min = ETP_YMIN_V1;
> + *x_max = ETP_XMAX_V1;
> + *y_max = ETP_YMAX_V1;
> + break;
> +
> + case 2:
> + if (etd->fw_version == 0x020800 ||
> + etd->fw_version == 0x020b00 ||
> + etd->fw_version == 0x020030) {
> + *x_min = ETP_XMIN_V2;
> + *y_min = ETP_YMIN_V2;
> + *x_max = ETP_XMAX_V2;
> + *y_max = ETP_YMAX_V2;
> + *y_2ft_max = ETP_2FT_YMAX;
> + break;
> + }

Actually these variables are defined as:
#define ETP_YMAX_V2 ( 768 - ETP_EDGE_FUZZ_V2)

I'd suggest to remove trying being too clever and remove the
ETP_EDGE_FUZZ_V2. They should be just the raw resolution of the device.
Otherwise, they can cause underflow on the Y axis.

Finally, a minor style suggestion, in "case 2:" above, only use one
single "break;" and put the two part in a complete "if-else" statement,
with xmin, y_min all explicit. E.g.:
case 2:
if (etd->fw_version == 0x020800 ||
etd->fw_version == 0x020b00 ||
etd->fw_version == 0x020030) {
*x_min = ETP_XMIN_V2;
*y_min = ETP_YMIN_V2;
*x_max = ETP_XMAX_V2;
*y_max = ETP_YMAX_V2;
} else {
i = (etd->fw_version > 0x020800 &&
etd->fw_version < 0x020900) ? 1 : 2;
*x_min = 0;
*y_min = 0;
*x_max = (etd->capabilities[1] - i) * 64;
*y_max = (etd->capabilities[2] - i) * 64;
}
break;

> If so, I will create another patch for this change.
>
If you could send a new version of this patch with these changes, it'd
be great :-)

Cheers,
Éric