Re: [PATCH v2] input: add EETI eGalax I2C capacitive multi touch driver.

Hi Henrik,

2011/8/13 Henrik Rydberg [off-list ref]:

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The device seems to send finger changes sequentually, resulting in one
packet (terminated with input sync) for each finger change. Is this
the intention/necessary? Some egalax firmware (hid version) seems to
work this way.

When I make v2 patch, I've a look the Protocol B's driver in upstream,
but there were two type of multi-point report fashion,
One type is report all the finger status in one input sync(), and
separate each mt point with mt_input_slot(), like wocom driver.

But there was some driver (like egalax hid version), send each mt
point with one input_sync(), but I'm worry about if main stream user
space frameworks(xorg mtouch etc,) support this behavior well.

Sequential reporting works reasonably well, although there are
potential problems (applying methods for smooth motion, for
instance). Wakeups and cpu intensity also increases.

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What's your point of view about this ?

If possible, I think batched reporting is preferred, i.e., using the
same method as all hid drivers _but_ the egalax one.

After go through the code, I found HID driver's batched report is hard
to implement in this driver.
Although, since I already use threaded irq to deal with the new event
information, and it will perform i2c read every time, i2c is a slow
bus, I think the CPU cause of this kind of device is relative lower
then some device via USB.

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The usage of REPORT_MODE_* is unclear to me too.

In the programming manual this mode 's name is "single touch mouse
mode", may be it will be a better name for this mode ?

Ok, sounds like the equivalent of the hid generic mouse, which could
either be ignored or assigned its own input device node. Nothing out
of the ordinary, in other words, and the patch looks good in this
respect. Thanks for clarifying.

I've already change the MODE_SINGLE to MODE_MOUSE to avoid confusion
in next version.

Henrik

Thanks,
Jiejing