Re: [PATCH V6 08/13] PCI: generic, thunder: update to use generic ECAM API

From: Tomasz Nowicki
Date: Thu Apr 21 2016 - 05:28:47 EST

On 19.04.2016 15:06, Arnd Bergmann wrote:
On Monday 18 April 2016 21:31:54 Tomasz Nowicki wrote:

Basically the whole content of pci-thunder-ecam.c and pci-thunder-pem.c.

pci-thunder-ecam.c contains config space accessors. Similar for
pci-thunder-pem.c but it also has extra init call (it is now called
thunder_pem_init) which finds and maps related registers.

They seem to do much more than just override the accessors, they actually
change the contents of the config space as well. Is that really necessary
on ACPI based systems as well?

Yes, the pci-thunder-ecam.c accessors are meant to emulate config space capabilities. They are necessary to synthesize EA capabilities (fixed PCI BARs), it wont work without this, for ACPI boot as well.

Another idea: how about moving all of this logic into ACPI and calling
some AML method to access the config space if the devices are that
far out of spec.

Do you mean Linux specific way to call non-standard config space accessors? Then non-standard accessors are going to AML methods which are called from common code which handles quirks via unified API ?