[hpoj-devel] parport_lowlevel/parport_probe module handling

[Burkhard K. <bu...@bu...>]

David Paschal
> Based on John Chmielewski's message from September 13, it sounds like it
> could be moved to (or possibly symlinked in) /lib/modules/misc, but there's
> still the problem that modprobe doesn't detect that ieee12844pp.o depends
> on parport_probe, not just parport and parport_pc.  My idea was to add a
> dummy function in ieee12844pp.c which never got called but which made a
> reference to a function in parport_probe (for example, parport_probe()).
> Since you're working on this code at the moment could you try this out and
> let me know if it fixes the problem (or I can try it myself later).

David, 

I have investigated that issue and to my surprise I found the following
lines in drivers/misc/parport_share.c:

/* Return a list of all the ports we know about. */
struct parport *parport_enumerate(void)
{
#ifdef CONFIG_KMOD
    if (portlist == NULL) {
        request_module("parport_lowlevel");
#ifdef CONFIG_PNP_PARPORT_MODULE
        request_module("parport_probe");
#endif /* CONFIG_PNP_PARPORT_MODULE */
    }
#endif /* CONFIG_KMOD */
    return portlist;
}

Thus, if "Kernel module loader" in "Loadable Module Support" and 
"Auto-probe for parallel devices" in "Plug and Play support" are
enabled parport_probe will be inserted by kmod automagically.
(A lsmod listing should mark parport_probe as "autoclean").

I have tested this with all parport relevant lines in modules.conf
commented out. After loading "parport.o" and "ieee12844.o" an
	insmod ieee12844pp.o 
loads "parport_pc.o" and "parport_probe.o"

I also looked into parport_probe.o and found that it only contains
a hook for the real probing function like "parport_probe_one".

Under 2.4 the situation is handled by the "parport_register_driver"
function which installs a lowlevel driver if not already present.

Burkhard
-- 
Burkhard Kohl			bu...@bu...