On Wed, Apr 19, 2006 at 10:08:57AM -0700, Kristen Accardi wrote: > On Tue, 2006-04-18 at 15:54 -0700, Patrick Mochel wrote: > > > +acpi_status > > > +register_hotplug_dock_device(acpi_handle handle, acpi_notify_handler handler, > > > + void *context) > > > > If this is called from outside drivers/acpi/, you should return an int with a > > real errno value. The AE_* values shouldn't be used outside of the ACPI CA. > > > > Really? We use these all over the place in drivers/pci/hotplug. In > fact, you kinda have to use them if you are calling certain acpi > symbols, since they return these types. > > For example, here are some functions will return acpi_status that we use > in hotplug land. > > pci_osc_control_set() > acpi_run_oshp() > acpi_walk_namespace requires its use. Well, it's one thing to use a function that returns a non-standard error-value, but it's another to add more functions that do. :-) > I felt that by returning acpi_status I was being consistent with how > other acpi calls acted. Is this another example of the iceberg that Len > was talking about in a previous email?? (ugh.) I believe so. We have a standard, well-defined error namespace that lives in include/*/errno.h. ACPI defines its own error namespace because it must be portable, and even though most OSes will define the standard errno values, some do not, so it cannot assume that it will be there. I'm not sure why the choice was to redefine similar error values instead of reusing the errno values, but that's moot at this point.. The only place where the ACPI error values need to be used is in the ACPI CA. The functions exposed to the OS from the CA will return AE_* because the same source runs everywhere. However, Linux-specific code doesn't need to do that. It is free to use Linux-specific error reporting (except in the OSL layer that the CA uses, because it is expecting well-defined return values, as specified in the CA Programmers Reference). My standpoint is that Linux-specific code should not be using any ACPI CAisms at all because since the code is Linux-specific, it doesn't need to be portable in the same manner that the CA is. This is true for all of drivers/acpi/*.c, with the exception of drivers/acpi/osl.c, but even some of that source can be cleaned up to be more Linux-friendly. Further rationale is that there is no way to enforce the CAisms in Linux-specific code. You will frequently find mixed return values. Sometimes a function is declared as acpi_status acpi_foo() and return -1 and 0. Or vice versa. The ACPI drivers were initially written in the same style that the CA was written, which makes it confusing when you look at them. But, they don't need to be that way. They can look like real Linux drivers and become a lot more palatable. Eventually, all of the CAisms should be pushed down to the thin layer that sits above the interpreter. All exported functions should return ints, and those that deal directly with the CA interface should simply translate the AE_* error values into an errno return. Thanks, Pat - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
