On Tue, 2024-01-16 at 23:17 +0200, andy.shevchenko@xxxxxxxxx wrote: > Mon, Jan 15, 2024 at 03:46:11PM +0100, Philipp Stanner kirjoitti: > > ¡Hola! > > i? Vim user? :-) The Dark Side of the Force is the path to many abilities, that some consider to be... unnatural https://www.neo-layout.org/ > > > PCI's devres API suffers several weaknesses: > > > > 1. There are functions prefixed with pcim_. Those are always > > managed > > counterparts to never-managed functions prefixed with pci_ – or > > so one > > would like to think. There are some apparently unmanaged > > functions > > (all region-request / release functions, and pci_intx()) which > > suddenly become managed once the user has initialized the device > > with > > pcim_enable_device() instead of pci_enable_device(). This > > "sometimes > > yes, sometimes no" nature of those functions is confusing and > > therefore bug-provoking. In fact, it has already caused a bug in > > DRM. > > The last patch in this series fixes that bug. > > 2. iomappings: Instead of giving each mapping its own callback, the > > existing API uses a statically allocated struct tracking one > > mapping > > per bar. This is not extensible. Especially, you can't create > > _ranged_ managed mappings that way, which many drivers want. > > 3. Managed request functions only exist as "plural versions" with a > > bit-mask as a parameter. That's quite over-engineered > > considering > > that each user only ever mapps one, maybe two bars. > > > > This series: > > - add a set of new "singular" devres functions that use devres the > > way > > its intended, with one callback per resource. > > - deprecates the existing iomap-table mechanism. > > - deprecates the hybrid nature of pci_ functions. > > - preserves backwards compatibility so that drivers using the > > existing > > API won't notice any changes. > > - adds documentation, especially some warning users about the > > complicated nature of PCI's devres. > > Instead of adding pcim_intx(), please provide proper one for > pci_alloc_irq_vectors(). Ideally it would be nice to deprecate > old IRQ management functions in PCI core and delete them in the > future. > In order to deprecate the intermingling with half-managed hyprid devres in pci.c, you need to have pci_intx() be backwards compatible. Unless you can remove it at once. And the least broken way to do that I thought would be pcim_intx(), because that's consistent with how I make pci_request_region() & Co. call into their managed counterparts. There are 25 users of pci_intx(). We'd have to look how many of them call pcim_enable_device() and how easy they would be to port to... pci_alloc_irq_vectors() you say? I haven't used that before. Would have to look into it and see how we could do that. P.
