> Unfortunately, commit 2fee61d22e (i2c: piix4: Add support for > multiplexed main adapter in SB800) [1] caused a regression. Tim > reported that to the Linux Kernel Bugtracker as bug #170741 last > September [2], but it looks like the affected subsystems don’t use it. Jean Delvare pointed out this issue amongst others[1] last year already. Let me quote: === 5* The I/O ports used for SMBus configuration and port switching are also needed by a watchdog driver, sp5100_tco. Both drivers request the region, so the first one wins, and the other driver can't be loaded. sp5100_tco was there first, so the changes done to the i2c-piix4 driver recently will cause a regression for some users by preventing them from using the sp5100_tco and i2c-piix4 drivers at the same time. In the long run I guess we will need a helper module to handle this shared resource. Unless IORESOURCE_MUXED can be used for that. Either way, that's more work than I can put into this before kernel v4.5 is released. For the time being, I think we should simply make it non-fatal if the I/O ports can't be requested, and continue without multiplexing (as before.) === Seems nobody had the resources, so far. I don't have the HW and not much experience with non-embedded platforms. I wonder, though, if we really need to convert the drivers to MFD ones, or if we could use the simpler MFD_SYSCON mechanism which helps in exactly such cases for embedded platforms. But I am really lacking details here and am afraid this is probably all the input I can give currently. Regards, Wolfram [1] http://www.spinics.net/lists/linux-i2c/msg23437.html
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