Date: Tue, 24 Jan 2023 19:15:30 +0000 From: "Dr. Rolf Jansen" <freebsd-rj@cyclaero.com> To: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: GPIO inputs on Pis? Message-ID: <01070185e534f221-14f362b5-2b96-43f0-b0b0-f496ad9994fe-000000@eu-central-1.amazonses.com> In-Reply-To: <fec41ff8-b658-36c8-615d-e3ae63dd9b37@denninger.net> References: <0b235f83-7cb3-1d14-7c64-aee7c1c0c23d@denninger.net> <01070185e46b1a6e-ee34b885-1215-45c7-ac18-83320c02cac2-000000@eu-central-1.amazonses.com> <a9b00748-1a11-3806-1103-ac2e6ad6bf43@denninger.net> <01070185e4732fd8-c0bede0b-d9df-4557-a174-cb237fa4bfaf-000000@eu-central-1.amazonses.com> <fec41ff8-b658-36c8-615d-e3ae63dd9b37@denninger.net>
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--Apple-Mail=_A11E81C7-9742-46CA-9F56-79152AC5767A Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > Am 24.01.2023 um 13:58 schrieb Karl Denninger <karl@denninger.net = <mailto:karl@denninger.net>>: >=20 > On 1/24/2023 10:43, Dr. Rolf Jansen wrote: >> I sent an old ink to the thread on the mailing list, which does not = work anymore. Here ist the new link: >>=20 >> = https://lists.freebsd.org/pipermail/freebsd-arm/2020-November/022738.html = <https://lists.freebsd.org/pipermail/freebsd-arm/2020-November/022738.html= > >>=20 >>> Am 24.01.2023 um 12:35 schrieb Karl Denninger <karl@denninger.net = <mailto:karl@denninger.net>>: >>>=20 >>> Thank you -- will check it out. >>>=20 >>> On 1/24/2023 10:35, Dr. Rolf Jansen wrote: >>>>> Am 23.01.2023 um 11:41 schrieb Karl Denninger <karl@denninger.net = <mailto:karl@denninger.net>>: >>>>>=20 >>>>> Is there support somewhere in the 13.x for other than "read = current state" / "set current state"? >>>>>=20 >>>>> Specifically, there is evidence in the sys/gpio.h header file that = I can open up a file descriptor and then use select()/read() to grab the = contents of a ring buffer of some size (presumably interrupt-posted) of = events since last look, and determine if there's anything in there. = Provided you're reasonably fast this might be enough to, for example, = read an optical encoder that has a modest pulse rate. >>>>>=20 >>>>> I see apparent review code at https://reviews.freebsd.org/D27398 = <https://reviews.freebsd.org/D27398>; from late 2020, but nothing else I = can find digging around; an example (assuming it is actually implemented = and works) would be helpful >>>>>=20 >>>> See >>>>=20 >>>> = https://forums.freebsd.org/threads/gpio-api-general-orange-pi-h3.83950/pos= t-556728 = <https://forums.freebsd.org/threads/gpio-api-general-orange-pi-h3.83950/po= st-556728> >>>>=20 >>>> And the messages in that thread that follow the one linked above. >>>>=20 >>>> There is a respective thread on this mailing list as well: >>>>=20 >>>> Porting FreeBSD to ARM processors: User Space GPIO Interrupt = programming - GSoC-2018 = <https://lists.freebsd.org/archives/freebsd-arm/2020-November/022740.html>= --=20 >>> Karl Denninger >>> karl@denninger.net <mailto:karl@denninger.net> >>> The Market Ticker >>> [S/MIME encrypted email preferred] >>=20 > So the answer at this point appears to be "not in the codebase and no = indication on when/if it might be, but there are patches that are in = some state of development.=E2=80=9C >=20 No, at this point (13.1-RELEASE) everything is in the kernel, no patches = needed. Even the test tool made it into the source tree. It has only be = renamed from gpioc_intr_test.c to gpioevents.c. /usr/src/tools/test/gpioevents/gpioevents.c The documentation is missing. It is however easy to learn how things = work by examining the code of gpioevents.c. > Being able to read an encoder of some sort basically means being able = to know how many events occurred between "looks"; for most purposes you = don't need each event delivered exactly when it occurs, but missing some = of the counts entirely is not acceptable. Yes, and for this reason, this GPIO event code which was developed by = Christian Kr=C3=A4mer in the course of the GSoC-2018 and has been = submitted in 2020 by Ian Lepore to the freebsd tree is perfect. Ian tested it with a 10 MHz sqaure wave on an imx6 (ARMv7, 1GHz) and got = an event every 10 =C2=B5s. That means the max. speed without event = losses would be 100 kHz. I did not do exact measurements, however, my = impression is that my RPi4B can do it a tad faster than my BeagleBone = Black. With the RPi4, I needed to improve the debouncing of the encoder = and the buttons, because it saw hundreds of bounces which the BBB = didn=E2=80=99t. However, it may also be, that the internal GPIO circuits = of the BBB have a different damping characteristic. Anyway for my applications, 100 kHz way faster than what I need. On my GitHub repository I placed another example on using the GPIO = events for the RPi: https://github.com/cyclaero/shutdd <https://github.com/cyclaero/shutdd>; See also the respective thread on this mailing list: https://lists.freebsd.org/archives/freebsd-arm/2022-July/001576.html = <https://lists.freebsd.org/archives/freebsd-arm/2022-July/001576.html>= --Apple-Mail=_A11E81C7-9742-46CA-9F56-79152AC5767A Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 <html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; = charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: = Verdana; font-size: 12px; font-style: normal; font-variant-caps: normal; = font-weight: normal; letter-spacing: normal; orphans: auto; text-align: = start; text-indent: 0px; text-transform: none; white-space: normal; = widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; = -webkit-text-stroke-width: 0px; text-decoration: none;" = class=3D""><blockquote type=3D"cite" class=3D""><div class=3D"">Am = 24.01.2023 um 13:58 schrieb Karl Denninger <<a = href=3D"mailto:karl@denninger.net" = class=3D"">karl@denninger.net</a>>:</div><br = class=3D"Apple-interchange-newline"><div class=3D""><div class=3D""><div = class=3D"moz-cite-prefix">On 1/24/2023 10:43, Dr. Rolf Jansen wrote:<br = class=3D""></div><blockquote type=3D"cite" = cite=3D"mid:01070185e4732fd8-c0bede0b-d9df-4557-a174-cb237fa4bfaf-000000@e= u-central-1.amazonses.com" class=3D""><div class=3D"" style=3D"word-wrap: = break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">I = sent an old ink to the thread on the mailing list, which does not work = anymore. Here ist the new link:<div class=3D""><br class=3D""></div><div = class=3D""><a = href=3D"https://lists.freebsd.org/pipermail/freebsd-arm/2020-November/0227= 38.html" class=3D"moz-txt-link-freetext" = moz-do-not-send=3D"true">https://lists.freebsd.org/pipermail/freebsd-arm/2= 020-November/022738.html</a></div><div class=3D""><br = class=3D""></div><div class=3D""><div class=3D""><blockquote type=3D"cite"= class=3D""><div class=3D"">Am 24.01.2023 um 12:35 schrieb Karl = Denninger <<a href=3D"mailto:karl@denninger.net" = class=3D"moz-txt-link-freetext" = moz-do-not-send=3D"true">karl@denninger.net</a>>:</div><br = class=3D"Apple-interchange-newline"><div class=3D""><div class=3D""><p = class=3D"">Thank you -- will check it out.<br class=3D""></p><div = class=3D"moz-cite-prefix">On 1/24/2023 10:35, Dr. Rolf Jansen wrote:<br = class=3D""></div><blockquote type=3D"cite" = cite=3D"mid:01070185e46b1a6e-ee34b885-1215-45c7-ac18-83320c02cac2-000000@e= u-central-1.amazonses.com" class=3D""><div class=3D""><blockquote = type=3D"cite" class=3D""><div class=3D"">Am 23.01.2023 um 11:41 schrieb = Karl Denninger <<a href=3D"mailto:karl@denninger.net" = class=3D"moz-txt-link-freetext" = moz-do-not-send=3D"true">karl@denninger.net</a>>:</div><br = class=3D"Apple-interchange-newline"><div class=3D""><div class=3D""><p = class=3D"">Is there support somewhere in the 13.x for other than "read = current state" / "set current state"?</p><p class=3D"">Specifically, = there is evidence in the sys/gpio.h header file that I can open up a = file descriptor and then use select()/read() to grab the contents of a = ring buffer of some size (presumably interrupt-posted) of events since = last look, and determine if there's anything in there. Provided = you're reasonably fast this might be enough to, for example, read an = optical encoder that has a modest pulse rate.</p><p class=3D"">I see = apparent review code at<span = class=3D"Apple-converted-space"> </span><a = class=3D"moz-txt-link-freetext" = href=3D"https://reviews.freebsd.org/D27398" = moz-do-not-send=3D"true">https://reviews.freebsd.org/D27398</a><span = class=3D"Apple-converted-space"> </span>from late 2020, but nothing = else I can find digging around; an example (assuming it is actually = implemented and works) would be = helpful</p></div></div></blockquote></div>See<div class=3D""><br = class=3D""></div><div class=3D""><a = href=3D"https://forums.freebsd.org/threads/gpio-api-general-orange-pi-h3.8= 3950/post-556728" class=3D"moz-txt-link-freetext" = moz-do-not-send=3D"true">https://forums.freebsd.org/threads/gpio-api-gener= al-orange-pi-h3.83950/post-556728</a></div><div class=3D""><br = class=3D""></div><div class=3D"">And the messages in that thread that = follow the one linked above.</div><div class=3D""><br = class=3D""></div><div class=3D"">There is a respective thread on this = mailing list as well:</div><div class=3D""><br class=3D""></div><div = class=3D""><a = href=3D"https://lists.freebsd.org/archives/freebsd-arm/2020-November/02274= 0.html" class=3D"" moz-do-not-send=3D"true">Porting FreeBSD to ARM = processors: User Space GPIO Interrupt programming - = GSoC-2018</a></div></blockquote><div class=3D"moz-signature">--<span = class=3D"Apple-converted-space"> </span><br class=3D"">Karl = Denninger<br class=3D""><a href=3D"mailto:karl@denninger.net" = class=3D"moz-txt-link-freetext" = moz-do-not-send=3D"true">karl@denninger.net</a><br class=3D""><i = class=3D"">The Market Ticker</i><br class=3D""><font class=3D"" = size=3D"-2"><i class=3D"">[S/MIME encrypted email = preferred]</i></font></div></div></div></blockquote></div><br = class=3D""></div></div></blockquote><p class=3D"">So the answer at this = point appears to be "not in the codebase and no indication on when/if it = might be, but there are patches that are in some state of = development.=E2=80=9C</p></div></div></blockquote>No, at this point = (13.1-RELEASE) everything is in the kernel, no patches needed. Even the = test tool made it into the source tree. It has only be renamed = from gpioc_intr_test.c to gpioevents.c.</div><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: = Verdana; font-size: 12px; font-style: normal; font-variant-caps: normal; = font-weight: normal; letter-spacing: normal; orphans: auto; text-align: = start; text-indent: 0px; text-transform: none; white-space: normal; = widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; = -webkit-text-stroke-width: 0px; text-decoration: none;" class=3D""><br = class=3D""></div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, = 0, 0); font-family: Verdana; font-size: 12px; font-style: normal; = font-variant-caps: normal; font-weight: normal; letter-spacing: normal; = orphans: auto; text-align: start; text-indent: 0px; text-transform: = none; white-space: normal; widows: auto; word-spacing: 0px; = -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; = text-decoration: none;" = class=3D"">/usr/src/tools/test/gpioevents/gpioevents.c</div><div = style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: = Verdana; font-size: 12px; font-style: normal; font-variant-caps: normal; = font-weight: normal; letter-spacing: normal; orphans: auto; text-align: = start; text-indent: 0px; text-transform: none; white-space: normal; = widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; = -webkit-text-stroke-width: 0px; text-decoration: none;" class=3D""><br = class=3D""></div><div style=3D"caret-color: rgb(0, 0, 0); color: rgb(0, = 0, 0); font-family: Verdana; font-size: 12px; font-style: normal; = font-variant-caps: normal; font-weight: normal; letter-spacing: normal; = orphans: auto; text-align: start; text-indent: 0px; text-transform: = none; white-space: normal; widows: auto; word-spacing: 0px; = -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; = text-decoration: none;" class=3D"">The documentation is missing. It is = however easy to learn how things work by examining the code of = gpioevents.c.</div><div style=3D"caret-color: rgb(0, 0, 0); color: = rgb(0, 0, 0); font-family: Verdana; font-size: 12px; font-style: normal; = font-variant-caps: normal; font-weight: normal; letter-spacing: normal; = orphans: auto; text-align: start; text-indent: 0px; text-transform: = none; white-space: normal; widows: auto; word-spacing: 0px; = -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; = text-decoration: none;" class=3D""><br class=3D""><blockquote = type=3D"cite" class=3D""><div class=3D""><div class=3D""><div = class=3D"">Being able to read an encoder of some sort basically means = being able to know how many events occurred between "looks"; for most = purposes you don't need each event delivered exactly when it occurs, but = missing some of the counts entirely is not = acceptable.</div></div></div></blockquote><div class=3D""><br = class=3D""></div><div class=3D"">Yes, and for this reason, this GPIO = event code which was developed by Christian Kr=C3=A4mer in the = course of the GSoC-2018 and has been submitted in 2020 by Ian Lepore to = the freebsd tree is perfect.</div><div class=3D""><br = class=3D""></div><div class=3D"">Ian tested it with a 10 MHz sqaure = wave on an imx6 (ARMv7, 1GHz) and got an event every 10 =C2=B5s. = That means the max. speed without event losses would be 100 kHz. I did = not do exact measurements, however, my impression is that my RPi4B can = do it a tad faster than my BeagleBone Black. With the RPi4, I needed to = improve the debouncing of the encoder and the buttons, because it saw = hundreds of bounces which the BBB didn=E2=80=99t. However, it may also = be, that the internal GPIO circuits of the BBB have a different damping = characteristic.</div><div class=3D""><br class=3D""></div><div = class=3D"">Anyway for my applications, 100 kHz way faster than what I = need.</div><div class=3D""><br class=3D""></div><div class=3D"">On my = GitHub repository I placed another example on using the GPIO events for = the RPi:</div><div class=3D""><br class=3D""></div><div class=3D""><a = href=3D"https://github.com/cyclaero/shutdd" = class=3D"">https://github.com/cyclaero/shutdd</a></div><div class=3D""><br= class=3D""></div><div class=3D"">See also the respective thread on this = mailing list:</div><div class=3D""><br class=3D""></div><div class=3D""><a= = href=3D"https://lists.freebsd.org/archives/freebsd-arm/2022-July/001576.ht= ml" = class=3D"">https://lists.freebsd.org/archives/freebsd-arm/2022-July/001576= .html</a></div></div></body></html>= --Apple-Mail=_A11E81C7-9742-46CA-9F56-79152AC5767A--
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