in finding compatibility there are 3 steps how to find
out whether the provided device driver supports currently
inserted device.
1. compare fields in the driver info structure
If there is a match (all CHECK_PARTIAL_COMPATIBILITY() macros return true),
we proceed to step 2.
If all device drivers are searched, but none is compatible ->
that means no device driver is available for currently inserted device.
2. try to call driver's init function.
If it return non-null pointer to data we may proceed to the step 3.
Otherwise, we continue in the loop handling step 1.
3. call analyze descriptor for all descriptors. When it returns true,
it means success and that the driver supports current device. From now on
poll function is allowed to be called.
If all descriptors were provided to the analyze_descriptor method and
it still returns false, it means device driver is not initialized and
should not be used with this device.
Signed-off-by: Amir Hammad <amir.hammad@hotmail.com>
