Hi all, I'm currently working on porting more drivers in DRM to managed pci- functions. During this process I discovered something that might be called an inconsistency in the implementation. First, there would be the pcim_ functions being scattered across several files. Some are implemented in drivers/pci/pci.c, others in lib/devres.c, where they are guarded by #ifdef CONFIG_PCI – this originates from an old cleanup, done in 5ea8176994003483a18c8fed580901e2125f8a83 Additionally, there is lib/pci_iomap.c, which contains the non-managed pci_iomap() functions. At first and second glance it's not obvious to me why these pci- functions are scattered. Hints? Second, it seems there are two competing philosophies behind managed resource reservations. Some pci_ functions have pcim_ counterparts, such as pci_iomap() <-> pcim_iomap(). So the API-user might expect that relevant pci_ functions that do not have a managed counterpart do so because no one bothered implementing them so far. However, it turns out that for pci_request_region(), there is no counterpart because a different mechanism / semantic was used to make the function _sometimes_ managed: 1. If you use pcim_enable_device(), the member is_managed in struct pci_dev is set to 1. 2. This value is then evaluated in pci_request_region()'s call to find_pci_dr() Effectively, this makes pci_request_region() sometimes managed. Why has it been implemented that way and not as a separate function – like, e.g., pcim_iomap()? That's where an inconsistency lies. For things like iomappings there are separate managed functions, for the region-request there's a universal function doing managed or unmanaged, respectively. Furthermore, look at pcim_iomap_regions() – that function uses a mix between the obviously managed function pcim_iomap() and pci_request_region(), which appears unmanaged judging by the name, but, nevertheless, is (sometimes) managed below the surface. Consequently, pcim_iomap_regions() could even be a little buggy: When someone uses pci_enable_device() + pcim_iomap_regions(), wouldn't that leak the resource regions? The change to pci_request_region() hasn't grown historically but was implemented that way in one run with the first set of managed functions in commit 9ac7849e35f70. So this implies it has been implemented that way on purpose. What was that purpose? Would be great if someone can give some hints :) Regards, P.
