Date: Mon, 19 Dec 2011 19:53:51 -0800 From: Adrian Chadd <adrian@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: Oleksandr Tymoshenko <gonzo@freebsd.org>, Stefan Bethke <stb@lassitu.de>, "freebsd-embedded@freebsd.org" <freebsd-embedded@freebsd.org> Subject: Re: Updated switch/glue patch? Message-ID: <CAJ-VmomySBQeMqr8meQDpSLBC1%2By_%2BvMQsSt9OWFaCA67O8G=w@mail.gmail.com> In-Reply-To: <CAJ-VmomERMdiMA7bzTeQyLR5YXXiJVXyjAzJfH6O-VvexpCcmg@mail.gmail.com> References: <CAJ-Vmon8%2BOXQ4g752zZEB-O0BR0sFWO0QUvw--xp2jsBDkx6tQ@mail.gmail.com> <0F6CC18F-6973-42A2-AC03-F01BF59458AE@lassitu.de> <CAJ-Vmo=Y8pp4iFnw%2B1hcPae6QXFboz=a7puwgC1kVSZ3JwMgPQ@mail.gmail.com> <1100F70E-9DA9-4163-AC9A-423ECE5AA9A3@lassitu.de> <CAJ-VmonrnJ7cC6u2LsL9AGusz_%2BkSwY62Rr1__sg5U_NynJ1SQ@mail.gmail.com> <CAJ-Vmo=WSN1oLM=B2HqSHrWyOaOD9BSwwu8=1Wys0CLRJ_N-TA@mail.gmail.com> <C637C171-A1A2-4296-84FA-6DE97137DC42@lassitu.de> <CAJ-Vmon2boy7OCh_4O0MeCi0yCdZu0OYb5dxHCEK=-%2B46zBGtg@mail.gmail.com> <CAJ-Vmoku5eLEYi5_DXVxK=0=4Ewn2aGepv3YUw4ApuVh_7y2%2Bw@mail.gmail.com> <CAJ-VmonvpnaS1rAO%2BsDRh1E5WfsrZTYE297Kc96prhfKjrM89Q@mail.gmail.com> <CAJ-VmokQxQs2DUKL=ONyxnnS7Q28ytmwZJ_thqvc4SvMkmS=cQ@mail.gmail.com> <18CABB46-9B9A-41CB-8742-6723C5FF4D67@lassitu.de> <C0BF20FD-E30F-4E9C-A0FE-500BE4807B99@bsdimp.com> <CAJ-VmokgiQCEG4et3X=3o_MuCMkO9MqkKqa-fjdpEqQNucn=Lw@mail.gmail.com> <2CBD8651-E132-49DC-A082-37A8F5C626EA@bsdimp.com> <CAJ-VmomERMdiMA7bzTeQyLR5YXXiJVXyjAzJfH6O-VvexpCcmg@mail.gmail.com>
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Hi, I've just dumped some more locking fixes into -HEAD. I've also changed iicbb.c a little so it has a configurable udelay. Sorry Stefan, you're going to have to rebase your iicbb changes. :) With the default per-bit sleep of 10uS, a rough calculation is: * 3 sleeps per bit: 30uS per bit * 8 bits per byte * 1 bit for ACK * == 12 bits per byte: 360uS a byte Each transaction is what, 5 bytes or 6 btyes total? I'll say 6 bytes, to be conservative. That's 2.1ms a transaction. Say thirty register accesses a second (for 5 switch PHY ports) - 63mS. I still think that's a bit low. But that's minimum 63mS of DELAY(), each second. Nothing else occurs during that. I've dropped the udelay parameter from 10 to 2 and had things work successfully. It still wastes a significant fraction of 100mS of CPU time each second. Sorry, but there has to be a better way to do this. Is it possible to just only poll a minimal set of PHY registers each second, rather than polling them all? Adrian
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