On Fri, May 24, 2019 at 11:00 AM 廖崇榮 <kt.liao@xxxxxxxxxx> wrote: > > Hi > > -----Original Message----- > From: Benjamin Tissoires [mailto:benjamin.tissoires@xxxxxxxxxx] > Sent: Friday, May 24, 2019 3:06 PM > To: 廖崇榮 > Cc: Dmitry Torokhov; Rob Herring; Aaron Ma; Hans de Goede; open list:HID CORE LAYER; lkml; devicetree@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 09/10] Input: elan_i2c - correct the width/size base value > > On Fri, May 24, 2019 at 5:13 AM 廖崇榮 <kt.liao@xxxxxxxxxx> wrote: > > > > Hi Benjamin, > > > > Thanks so much for all you do for Elan touchpad. > > > > For the width_*, I have a question for it. > > Our antenna sensors fully occupied the whole touchpad PCB. > > > > The Gap between 2 sensors are 7.5 mil (0.19mm). > > That's why we did not minus one trace. > > So, with the P52 I have: > [ +0.000009] max: (3045,1731) drivers/input/mouse/elan_i2c_core.c:428 > [ +0.000003] traces: (24,14) drivers/input/mouse/elan_i2c_core.c:429 > [ +0.000002] size: (98,55) drivers/input/mouse/elan_i2c_core.c:430 > [ +0.000001] res: (31,31) drivers/input/mouse/elan_i2c_core.c:431 > > calculated size (max/res): 98 x 56 mm > true size, as measured: 101 x 60 mm > > I list layout information of P52 touchpad as below. > Physical size : 99 x 58 mm > Active Area size : ~ 97 * 56 mm, (boarding is 1.008mm for each side) > > Sensor layout: > X Pitch : 4.0286 mm > Y Pitch : 4.0147 mm > > Which gives (without the minus 1): > width_x = max_x / x_traces = 3045 / 24 = 126.875 -> 3.9885 mm width_y = max_y / y_traces = 1731 / 14 = 123.643 -> 4.0927 mm > > -> this gives a total size of the touchpad of: 96 x 57 mm (width_x * > 24, width_y * 14) > > With the minus 1: > width_x = max_x / x_traces = 3045 / 23 = 132.391 -> 4.2707 mm width_y = max_y / y_traces = 1731 / 14 = 133.154 -> 4.2953 mm > > -> this gives a total size of the touchpad of: 102 x 60 mm (width_x * > 24, width_y * 14) > and considering traces-1: 98 x 56 mm > > Removing 1 to the number of traces gave a squarer values in rows and columns, and this is what is done in the PS/2 driver. > Also, going back to the size of the touchpad gives a better value when removing 1 on the *traces. > So maybe when forwarding the properties we should remove one there in the PS/2 driver? > > Removing 1 trace may be better for some of previous touchpad. (depending on sensor pattern) > mk_* indicate the number of trace which is touched, and it's not a precise value. > I think the usability won't change too much whether removing one trace. > PS/2 have supported plenty of touchpad. It's better to remain the same. > OK, so I guess I should just drop this patch from the series then. Cheers, Benjamin
