[Ksummit-discuss] [TECH TOPIC] Driver model/resources, ACPI, DT, etc (sigh)

[Benjamin Herrenschmidt]

On Sun, 2014-05-04 at 23:33 +0200, Rafael J. Wysocki wrote:
> 
> 
> But we have such quirks for some bus types already, like PCI and PNP.

And they suck big time. They duplicate definitions from the driver,
they get missed at grep time, they bit rot, etc...

There are a few cases where that's justified simply because the driver
can be a module but the quirk needs to run early and always, but mostly
these quirks are about working around HW bugs that would otherwise cause
the system to misbehave even in absence of the driver.

For example, bad class code in bridges, BAR issues, etc...

Generally speaking though, quirks like that are a bad idea and in this
case, totally unjustified since the code performing whatever translation
is necessary (or interpretation) is entirely specific to the driver
anyway.

Also if the bindings evolve, you just created a 3rd way dependency.
Instead of just having to deal with DT/ACPI binding version vs. driver
version, we now have to also handle quirk versioning.


Cheers,
Ben.