Basically what I was asking is whether I could use i2c_generic_scl_recovery
in the case where SCL is hung.

The name is a bit misleading, I am afraid. Recovery can only be used when
SDA is stuck low. And to fix this it *uses* SCL toggling to get out of
it. And 'generic_scl' means 'gimme some SCL to control and I will toggle
it'. Compared to 'gpio_recovery' which will do all the GPIO handling for
you.

When SCL is hung, you can only reset the device which forces SCL low.

I think I have a pretty good idea of what to do, I should probably just put
together an RFC patch.

Sure.