Ticket #404 (Fixed)Wed Mar 11 18:36:53 UTC 2015
Attempting to probe IIC buses misbehaves and trashes CMOS RAM settings
| Reported by: | Rick Murray (539) | Severity: | Major |
| Part: | RISC OS: General | Release: | |
| Milestone: | Status | Fixed |
Details by Rick Murray (539):
As described here ( https://www.riscosopen.org/forum/forums/4/topic… ) along with a code snippet, the idea is to attempt to talk to a specific IIC device by stepping through each IIC bus and looking for the correct reply.
Expected behaviour would be to have non-existent devices/buses throw an error.
Behaviour seen is… rather different.
Testing on a Pi, with the device on IIC bus 0, there are phantom gibberish replies on buses 2, 4, and 6.
Testing on a Pi, attempting to talk to the device on bus 5 fails (no phantoms) but subsequently RISC OS has not only reverted all CMOS RAM settings to defaults, they are LOCKED in that state. You can’t alter any configuration held in “CMOS RAM” until the machine has been rebooted. It is for this unexpected and unpleasant behaviour that I class this problem as Major. Phantom responses are one thing, trashing user settings is something altogether different.
I have conducted my tests on a Pi(v1), Chris Evans indicates that similar behaviour is also occurring on Pandaboards.
Changelog:
Modified by Jeffrey Lee (213) Mon, March 16 2015 - 21:31:21 GMT
- Status changed from Open to Fixed
Should be fixed with Kernel-5_35-4_79_2_260. You’ll now get a ‘Parameters not recognised’ error instead of a crash or other unpredictable behaviour.
