Date: Tue, 10 Oct 2017 19:20:25 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Ian Lepore <ian@FreeBSD.org>, src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org Subject: Re: svn commit: r323465 - head/usr.sbin/i2c Message-ID: <f451de74-554c-6782-d954-4964683775db@FreeBSD.org> In-Reply-To: <1507651963.84167.37.camel@freebsd.org> References: <201709112149.v8BLncAs049328@repo.freebsd.org> <4c4a916f-9960-6d7f-3389-37b998ba980b@FreeBSD.org> <1507651963.84167.37.camel@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 10/10/2017 19:12, Ian Lepore wrote: > i2c -s is not a thing that's done routinely in a production system or > normal system operations... it's something a person does manually when > trying to configure or debug a system. In that situation, there is > more harm in being told there are no working devices on the bus when in > fact everything is fine, than there is some some hypothetical device > doing some hypothetical "bad thing" in response to a read command. In > all my years of working with i2c stuff I've never seen a device doing > anything more harmful than hanging the bus, requiring a reset (and even > causing that requires worse behavior than an unexpected read). On the > other hand, I've seen a lot of people frustrated that i2c -s on freebsd > says there are no devices, while the equivelent command on linux shows > that everything is fine. Okay. However, I will just mention that in the past I used to own a system where scanning the bus would make a slave that controlled CPU frequency to change it to some garbage. The system "just" crashed, but theoretically the damage could have been worse. Also, I own a system right now where scanning the bus results in something like what you mentioned, but a little bit worse, the hanging bus that can be brought back only by a power cycle (not even a warm reset). -- Andriy Gapon
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?f451de74-554c-6782-d954-4964683775db>