P5A board: i2c-ali15x3 fails while i2c-isa works (Examined/Solved - lm_sensors 2.4.5 Linux-2.2.14)

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This is just a FYI, not really a bug report, to maybe save some people some time. On my ASUS P5A board, I have used Linux-2.0.x and lm_sensors-1.4.11 successfully for ages. With the kernel upgrade to 2.2.14, however, I also wanted to upgrade to lm_sensors-2.4.5, and that has given me the following situation: The hardware probing shell script suggested to use the i2c-ali15x3 module and the w83781d module. At first, this appeared to work fine, however after several calls to sensors the SMbus appeared to hang, the kernel modules would report timeouts and reset attempts over and over again. Just as mentioned in other tickets (thx for the excellent ticket system BTW), my machine could then no longer be powered down by software, a power cut was required to get it going again. Now I suppose the older 1.4 version had no support for the ALI15x3 chipset, so I just tried the ISA module. Simply replacing i2c-ali15x3 with i2c-isa has done the job: I can now call sensors as often as I like, and everything seems to be fine (it also feels a bit faster now). Maybe sensors-detect could be changed so that it prefers i2c-isa to i2c-ali15x3, but of course I cannot say which circumstances would justify this. Regards, Wolfram.

--- Thanks for your excellent report. You can actually tell sensors-detect what you prefer. But when you choose ISA, you usually have to tell the driver to not to attach to the ALI driver (which you still may want to load for other things, like EEPROMs). ISA is always faster then SMBus (ISA uses your bus speed, which in the tens of MHz; SMBus uses the SMBus speed which is in the tens of KHz). I wish we could fix the ALI and PIIX4 drivers; but it seems a real hardware problem that can't be solved through software. Or the software fix is too esoteric to find by accident, and it is not documented anywhere :-(

Frodo