Date: Fri, 27 Nov 2020 11:04:05 -0700 From: Ian Lepore <ian@freebsd.org> To: freebsd-arm@freebsd.org Subject: Re: User Space GPIO Interrupt programming - GSoC-2018 Message-ID: <1e6993d43d22d6ce1aa2860a61745356688d1e53.camel@freebsd.org> In-Reply-To: <08649892ca2ab434c261d36e0e13ba051086de6f.camel@freebsd.org> References: <2B01780F-D367-48A3-A827-B479030A496D@obsigna.com> <c55d7f332631b69c3241a60538a6a7b5475d93b9.camel@freebsd.org> <FBEF19B1-0504-4CDF-976C-C50707E06584@obsigna.com> <8d806302-479c-ca34-3fdb-96d27f40e212@viruzzz.org> <8655AF30-273B-48E7-98CD-007AA1D265F5@obsigna.com> <54ffe2d2-01a2-8b43-94fa-aee4a3f89861@viruzzz.org> <08649892ca2ab434c261d36e0e13ba051086de6f.camel@freebsd.org>
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On Fri, 2020-11-27 at 10:16 -0700, Ian Lepore wrote: > On Fri, 2020-11-27 at 14:28 +0300, Vladimir Goncharov wrote: > > Here it is. > > There is struct gpioc_event with pin number and bintime which is send > > to userspace. > > > > Also I'm thinking about to implementation notofication without extra > > reading from socket via struct kevent's extra fields (fflags/ext[4]), > > looks like it is possible. > > > > Please don't top-post on freebsd mailing lists. > > I think we need a way for the app to choose whether it wants simple > reporting of pin number (like the original code) perhaps along with a > count, versus requesting detailed per-event data. I'm going to propose > something more detailed about this as soon as I get my thoughts all > organized. I also want to get the original code and the locking fixes > I've done to it into a phab review for people to start looking at > before starting to do new major changes to it. > > Allocating memory in the interrupt handler isn't a good idea, it will > just increase latency on processing other pin interrupts and lead to > inaccurate timestamps. IMO, it would be better to allocate a fixed > array of events; when the app requests detailed event reporting it can > request the number of stored events it wants handled and we could > allocate all at once based on that. > The gsoc2018 code, with locking and style(9) fixes, is now at: https://reviews.freebsd.org/D27398 -- Ian
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