User Space GPIO Interrupt programming - GSoC-2018

[Dr. Rolf Jansen]

Hello Vladimir,

yes please, I am interested. Please can show us your version of the GSoC-2018 diff file?

Best regards

Rolf

> Am 27.11.2020 um 05:02 schrieb Vladimir Goncharov <freebsd at viruzzz.org>:
> 
> Hello Rolf,
> 
> I have implemented in kernel queue for generated GPIO interrupts with
> timestamps, so now it's possible to catch all events even on busy
> system. It's all for gpio_gsoc2018 code. In result I have no more
> warnings in dmesg. Unfortunately it requires allocating memory on each
> event to store pin number and timestamp. In case of unability allocating
> memory it falls back to gpio_gsoc2018 method.
> Does anybody interested in such patches?
> 
> 
> 2020-11-27 04:18, Dr. Rolf Jansen пишет:
>>> Am 26.11.2020 um 16:56 schrieb Ian Lepore <ian at freebsd.org>:
>>> 
>>> On Tue, 2020-11-24 at 17:14 -0300, Dr. Rolf Jansen wrote:
>>>> Hello
>>>> 
>>>> Has anything of the GSoC-2018 efforts made it into the current code
>>>> base?
>>>> 
>>>> 
>>> https://wiki.freebsd.org/SummerOfCode2018Projects/UserSpaceGPIOinterrupts
>>>> 
>>>> I installed the recent 13.0-CURRENT snapshot (2020-11-19) on a
>>>> BeagleBone Black which was one of the implementation targets of said
>>>> project, but when running the test tools, I either see cannot
>>>> read/kevent/poll/aio_read - Operation not supported by device or
>>>> Inappropriate ioctl for device.
>>>> 
>>>> Perhaps I need to pull the project´s changes into the kernel by
>>>> myself. However, before this I would like to ask whether it is worth
>>>> the effort.
>>>> 
>>>> Please, can anyone shed some light on this.
>>>> 
>>>> Best regards
>>>> 
>>>> Rolf
>>>> 
>>> 
>>> I made some time this morning to review the gsoc2018 code.  It turns
>>> out this code is very high quality, nearly ready to commit as-is.  The
>>> main thing it needs is some style cleanup in its comment blocks, and
>>> documentation.  I'd be inclined to commit the code first and write the
>>> documentation over the next little while and commit it separately.
>>> 
>>> If you'd like to give it a try, here's a diff that should apply and
>>> build cleanly on freebsd 12 or 13:
>>> 
>>> https://people.freebsd.org/~ian/gpio_gsoc2018.diff
>>> 
>>> While there isn't any documentation yet, there is a test program (I
>>> haven't run it yet) that demonstrates all the features:
>>> 
>>> https://github.com/ckraemer/gsoc2018-utils/blob/master/src/gpioc_intr_test.c
>>> 
>>> Right now the code will let you block waiting for a pin-change event
>>> using select(), poll() or kevents, or to be notified via SIGIO, but
>>> after being notified that something happened, you still have to call
>>> read() to see which pin changed.  I think if the pin changes state
>>> multiple times between calls to read(), you'll lose track of some
>>> changes (I'm not positive of that, I don't understand the kevent stuff
>>> well).
>>> 
>>> I'd like to add some features so that you can configure it to track pin
>>> changes in counting-mode and timestamping-mode.  In counting mode, when
>>> you do a read() you would get back a pair of values, the pin number and
>>> how many times its interrupt fired since the last read.  In
>>> timestamping mode, every read would return a pin number and an
>>> associated timespec giving the exact time the interrupt happened (there
>>> would need to be a way to configure how many events it could buffer,
>>> but I think even allowing a thousand buffered events would only use a
>>> few kbytes of memory).
>> 
>> I got it working as well, please see my other post from yesterday. I used gpioc_intr_test.c.
>> 
>> I see hundreds of warning messages when I press the test button a few times. May these warnings be safely ignored. The kernel module of Oskar Holmund works quite nice as well (for what I need), and with that one, I don’t see warnings.
>> 
>> The counting- and timestamping-mode for sure would be very useful. Perhaps by implementing this, there won’t be no unhandled interrupts anymore, and hence there won’t be any warnings either.
>> 
>> Best regards
>> 
>> Rolf
>> 
>> 
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Dr. Rolf Jansen
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