Date: Sun, 16 May 2021 06:51:30 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Ian Lepore <ian@freebsd.org> Cc: hackers@freebsd.org Subject: Re: patch: make i2c(8) usable for scripting Message-ID: <13972.1621147890@critter.freebsd.dk> In-Reply-To: <8d232feb354bf404426c51efe4953551ae2476c9.camel@freebsd.org> References: <12056.1621109641@critter.freebsd.dk> <8d232feb354bf404426c51efe4953551ae2476c9.camel@freebsd.org>
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-------- Ian Lepore writes: > On Sat, 2021-05-15 at 20:14 +0000, Poul-Henning Kamp wrote: > > The /dev/iic%d filedescriptor is opened and closed for every single > > command, in the hope that it will aid multiple separate programs > > sharing I2C busses. I have not actually tried that yet, so it may > > need more work (exclusive opens etc.). > > There should be no need to do that. The i2c bus is arbitrated in > iicbus/iiconf.c and most all the in-tree drivers now use either > explicit iicbus_request_bus() calls, or use iicbus_transfer_excl(). = > Certainly users of iic(4) don't need to be protected from each other; > everything in the driver that uses the bus does so inside of > request_bus / release_bus calls. How does that work when i2c(8) (by default) issues discrete start/stop com= mands ? Related to that: Should i2c(8)'s -m default be changed to 'tr' ? -- = Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe = Never attribute to malice what can adequately be explained by incompetence= .
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