On Tue, 2017-10-10 at 19:20 +0300, Andriy Gapon wrote: > 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). >
These systems didn't used to hang on i2c -s, and now they do? -- Ian _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
