[fprint] Documentation for writing a new driver

[Mark Harfouche]

Alright, I think I finally got somewhere.

I can run img_capture successfully. I see two pgm files in my directory
that look like fingerprints.

This particular device can’t do the matching so it all has to be done on
the host.
I assume libfprint can do this?

I can’t seem to run enroll. This is the output I get:

This program will enroll your right index finger, unconditionally
overwriting any right-index print that was enrolled previously. If you
want to continue, press enter, otherwise hit Ctrl+C

Found device claimed by Validity VFS7552 driver
Opened device. It's now time to enroll your finger.

You will need to successfully scan your finger 5 times to complete the process.

Scan your finger now.
Wrote scanned image to enrolled.pgm
Didn't quite catch that. Please try again.

Scan your finger now.
libusb: warning [handle_timeout] async cancel failed -5 errno=22
Wrote scanned image to enrolled.pgm
Didn't quite catch that. Please try again.

What is:

libusb: warning [handle_timeout] async cancel failed -5 errno=22

Help would be appreciated, though I know it is difficult to debug other
people’s hardware.

Mark
​

On Fri, Mar 9, 2018 at 11:02 AM, Igor Filatov <ia.filatov at gmail.com> wrote:

> Not really. The same state is sent to dev_change_state after activation
> has ended with fpi_imgdev_activate_complete. You can ignore it.
>
>
> On Fri, Mar 9, 2018 at 8:51 PM Mark Harfouche <mark.harfouche at gmail.com>
> wrote:
>
>> Hi Igor,
>>
>> Thank you for your reply.
>>
>> I’m confused about the parameter sent to dev_activate. Is it useful? in
>> uru4000.c (which seems to be the latest one written), the authors also seem
>> to be confused
>>
>> /* FIXME: having state parameter here is kinda useless, will we ever
>>  * see a scenario where the parameter is useful so early on in the activation
>>  * process? asynchronity means that it'll only be used in a later function
>>  * call. */static int dev_activate(struct fp_img_dev *dev, enum fp_imgdev_state state)
>> {
>>
>> Thanks,
>>
>> Mark
>>
>> On Fri, Mar 9, 2018 at 10:43 AM, Igor Filatov <ia.filatov at gmail.com>
>> wrote:
>>
>> Hi Mark,
>>>
>>> There are no high-level docs, unfortunately. There's some valuable info
>>> in comments in drv.c, sync.c, async.c, img.c etc. but it only covers
>>> specific parts, not how they should interact.
>>>
>>> There are 6 drivers for press-type sensors: aes3500.c, aes4000.c,
>>> fdu2000.c, upektc.c, uru4000.c, vcom5s.c. But there isn't much difference
>>> between press and swipe drivers. FP_SCAN_TYPE_* is used to determine which
>>> messages to show ("please touch the sensor" vs. "please swipe..."), and I
>>> think that's it. Besides that, all drivers essentially do the same thing:
>>> obtain the fingerprint image and submit it. You can use any driver as a
>>> reference.
>>>
>>>
>>>
>>> On Fri, Mar 9, 2018 at 7:50 PM Mark Harfouche <mark.harfouche at gmail.com>
>>> wrote:
>>>
>>>> Hello all,
>>>>
>>>> I would like to develop a driver for the Validity 0091 sensor available
>>>> on the Dell XPS13/15 9X60.
>>>>
>>>> I would say I have the driver reverse engineered to 95% (There might be
>>>> a few things I still don’t understand from the internal state machine).
>>>> https://github.com/hmaarrfk/Validity91
>>>> WIP: https://github.com/freedesktop/libfprint
>>>>
>>>> I found the libfprint source, can compile it, and started creating my
>>>> own driver.
>>>>
>>>> However, I am confused about the internal workings of libfprint and the
>>>> functions I need to define.
>>>> I tried to follow examples that were included, but it seemed that they
>>>> were mostly “swipe”‘ sensors, and not capacitive style sensor.
>>>> Is there any good documentation about the state machines I need to
>>>> implement with regards to the functions
>>>>
>>>>     .open = dev_open,
>>>>     .close = dev_close,
>>>>     .activate = dev_activate,
>>>>     .deactivate = dev_deactivate,
>>>>     .change_state = dev_change_state,
>>>>
>>>> Thanks,
>>>>
>>>> Mark
>>>> ​
>>>> _______________________________________________
>>>> fprint mailing list
>>>> fprint at lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/fprint
>>>>
>>> ​
>>
>
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