From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4CB85035.4060409@domain.hid> Date: Fri, 15 Oct 2010 14:59:33 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <4CB06CE9.9090204@domain.hid> <1287070938.1628.20.camel@domain.hid> <4CB72B5D.1070304@domain.hid> <1287073013.1628.25.camel@domain.hid> <4CB743FA.20504@domain.hid> <4CB7482C.9060602@domain.hid> <4CB753EC.9010107@domain.hid> <4CB75976.6040302@domain.hid> <4CB7F73F.2050509@domain.hid> <4CB835DE.3060600@domain.hid> <4CB84D5D.6090106@domain.hid> In-Reply-To: <4CB84D5D.6090106@domain.hid> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig75154C163CF34ABFA9A49E5B" Sender: jan.kiszka@domain.hid Subject: Re: [Xenomai-core] [forge] irqbench removal List-Id: Xenomai life and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wolfgang Grandegger Cc: Xenomai core This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig75154C163CF34ABFA9A49E5B Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Am 15.10.2010 14:47, Wolfgang Grandegger wrote: > On 10/15/2010 01:07 PM, Wolfgang Grandegger wrote: >> On 10/15/2010 08:39 AM, Jan Kiszka wrote: >>> Am 14.10.2010 21:26, Wolfgang Grandegger wrote: >>>> On 10/14/2010 09:03 PM, Jan Kiszka wrote: >>>>> Am 14.10.2010 20:13, Wolfgang Grandegger wrote: >>>>>> Hi Jan, >>>>>> >>>>>> On 10/14/2010 07:55 PM, Jan Kiszka wrote: >>>>>>> Am 14.10.2010 18:16, Philippe Gerum wrote: >>>>>>>> On Thu, 2010-10-14 at 18:10 +0200, Jan Kiszka wrote: >>>>>>>>> Am 14.10.2010 17:42, Philippe Gerum wrote: >>>>>>>>>> On Sat, 2010-10-09 at 15:23 +0200, Jan Kiszka wrote: >>>>>>>>>>> Philippe, >>>>>>>>>>> >>>>>>>>>>> irqbench does not inherently depend on a third I-pipe domain.= It is a >>>>>>>>>>> useful testcase, the only in our portfolio that targets a per= ipheral >>>>>>>>>>> device use case. In fact, it was only of the first test cases= for Native >>>>>>>>>>> RTDM IIRC. >>>>>>>>>>> >>>>>>>>>>> Please revert the removal and then cut out only the few parts= that >>>>>>>>>>> actually instantiate an additional domain (i.e. mode 3. >>>>>>>>>> >>>>>>>>>> So, what do we do with this? Any chance we move to arch-neutra= l code for >>>>>>>>>> this test? >>>>>>>>> >>>>>>>>> Arch-neutral is impossible due to the inherent hardware depende= ncy. But >>>>>>>>> I'm waiting on some comments by Wolfgang on their work as that'= s >>>>>>>>> probably the best requirements source for multi-arch support. >>>>>>>> >>>>>>>> I mean that the bulk of the code could be made arch-neutral, wit= h only >>>>>>>> callouts to solve the arch-dependent/uart issues. Typically, 165= 50's are >>>>>>>> not uncommon on powerpc, but we obviously don't program them via= >>>>>>>> ioports. A second level of indirection could provide the entire = chip >>>>>>>> handling, to fit other uarts, maybe? >>>>>>> >>>>>>> If there are suitable UARTs around, refactoring the code accordin= gly and >>>>>>> maybe adding support for one of them as reference would be a good= next >>>>>>> step. But first I would like to understand (or recall - I think W= olfgang >>>>>>> once explained it) the motivations for not going this path with t= he >>>>>>> gpiobench test and learn its requirements to avoid doing refactor= ings >>>>>>> twice or more. >>>>>> >>>>>> Well, it's a long time ago that I wrote gpioirqbench, which is der= ived >>>>>> from Jan's irqbench. Obviously, it uses GPIO pins to signal events= >>>>>> instead of signals from the parallel port or serial line. I never >>>>>> supported the serial line for embedded boards. >>>>> >>>>> What was the reason? That it is too often blocked by a terminal? >>>> >>>> Mainly because there is no RTserial driver for the serial interface = on >>>> the embedded boards, e.g. for the PSC, SCC. Furthermore, they are >>>> usually handled by firmware with ring buffers, dma, etc. which would= >>>> introduce additional delays. They might be negligible, though. >>>> >>>>>> You can get the code with: >>>>>> >>>>>> $ git clone git://git.denx.de/gpioirqbench >>>>>> >>>>>> It uses a simple hw abstruction layer defined in target/gpioirq-hw= =2Eh: >>>>>> >>>>>> http://git.denx.de/?p=3Dgpioirqbench.git;a=3Dblob;f=3Dtarget/gpioi= rq-hw.h;h=3D76849da0964c7dbb6831fe02374922dcf89b3bb1;hb=3DHEAD >>>>> >>>>> Is this abstracting the target side, right? >>>> >>>> Yep. >>>> >>>>>> Don't know if it's generic enough to support the parallel and seri= al >>>>>> port interface as well. Anyway, with working generic GPIO lib supp= ort, >>>>>> it's quite simple to support new hardware, e.g. i.MX31 boards. >>>>>> >>>>>> The host side to measure precisely the latency is even more tricky= =2E >>>>> >>>>> Depends. If you can map the GPIO output on something RS232 or paral= lel >>>>> port compatible, you are done. Usually, there is always some x86 bo= x >>>> >>>> THe GPIO lines of most embedded boards don't like 5V. The are specif= ied >>>> for 3.3V plus something less than 5V. I was thinking about that alre= ady >>>> but finally didn't want to damage the board. A 3.3V serial interface= on >>>> the PC would be fine, though. >>> >>> Sounds like we just need a voltage divider for RS232 -> GPIO. The oth= er >>> way should be fine as everything above 3 V is considered High, and I >>> think to remember that even the invalid range of +/-3 V is reported a= s >>> Low by typical (PC-)UARTs. >> >> I just googled around a bit and found: >> >> http://www.rs232-converters.com/rs232-to_ttl3.3_converters.htm >=20 > Or at ebay: http://shop.ebay.at/i.html?_kw=3Dttl&_kw=3Dconverter >=20 Look perfect on first sight - but not on second: They all convert RX/TX, but we need status line conversions. So you need at least some re-wiring via a breakout box a special cable. Still, it's a good base to build upon= =2E Jan --------------enig75154C163CF34ABFA9A49E5B Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org/ iEYEARECAAYFAky4UDgACgkQitSsb3rl5xQ0gQCdHuh6YJAVIyUGQsNUOw/guhvA boYAoLHiA2sNatPLxjRFplqPOjaJUlYL =OElJ -----END PGP SIGNATURE----- --------------enig75154C163CF34ABFA9A49E5B--