Re: [PATCH] ACPI: make acpi_bus_register_driver() return zero for success, not device count

[Bjorn Helgaas <bjorn.helgaas-VXdhtT5mjnY@public.gmane.org>]

On Thursday 28 July 2005 5:58 am, Karol Kozimor wrote:
> Thus wrote Bjorn Helgaas:
> > pci_register_driver() used to return the number of devices claimed,
> > and we made acpi_bus_register_driver() consistent with that.  But
> > pci_register_driver() recently changed to return only success/failure
> > (because the interface is to register the *driver*, not claim devices,
> > and devices may be hot-plugged later).
> > 
> > So let's do the same with acpi_bus_register_driver().
> > 
> > Note that asus_acpi.c used to unregister itself if it didn't claim
> > any devices.  Now it will remain registered, like everything else
> > in drivers/acpi.
> 
> Ugh, not again... we've been there (early 2.6.x), done that and it was
> absolutely confusing (I mean users reporting bogus bugs just because the
> module was loaded type of confusing). Note that there's currently no easy
> way to probe for a specific HID in ACPI namespace other than
> acpi_bus_register_driver(), and unlike pci_register_driver() the former
> has no hotplug mechanism to help. 

True.  But your driver can use its own mechanism to determine whether
it claimed any devices, and if not, call acpi_bus_unregister_driver()
and then return -ENODEV from the module init function to cause the
module to be unloaded.

Or is there some problem that would prevent that?


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