On Mon, Jun 18, 2012 at 12:30 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > On Sun, Jun 17, 2012 at 10:03 PM, Ram Pai <linuxram@xxxxxxxxxx> wrote: >> PCI: methods to access resources of struct pci_dev >> >> Currently pci_dev structure holds an array of 17 PCI resources; six base >> BARs, one ROM BAR, four BRIDGE BARs, six sriov BARs. This is wasteful. >> A bridge device just needs the 4 bridge resources. A non-bridge device >> just needs the six base resources and one ROM resource. The sriov >> resources are needed only if the device has SRIOV capability. >> >> The pci_dev structure needs to be re-organized to avoid unnecessary >> bloating. However too much code outside the pci-bus driver, assumes the >> internal details of the pci_dev structure, thus making it hard to >> re-organize the datastructure. >> >> As a first step this patch provides generic methods to access the >> resource structure of the pci_dev. >> >> Once this patch is accepted, I have another 40+ patches that modify all >> the files that directly access the resource structure, to use the new >> methods provided in the first step. >> >> Finally we can re-organize the resource structure in the pci_dev >> structure and correspondingly update the methods. > > I have patchset on this, please check > > git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git > for-pci-for-each-res-addon I don't like the pci_dev.resource[] table very well either, and I don't like the fact that drivers access it directly. So I do think we need some sort of abstraction that lets us change the way we store the resources without affecting the callers. Both of these (Ram's patch: http://marc.info/?l=linux-pci&m=133999604128815&w=2 and Yinghai's patch: http://git.kernel.org/?p=linux/kernel/git/yinghai/linux-yinghai.git;a=commitdiff;h=cd192f0ed93203ef6bac2a44c138899190fb5793) have a similar approach of adding many iterators. Yinghai's adds: for_each_pci_dev_all_resource for_each_pci_dev_nobridge_resource for_each_pci_dev_base_resource for_each_pci_dev_base_norom_resource for_each_pci_dev_base_iov_norom_resource for_each_pci_dev_noiov_resource for_each_pci_dev_std_resource for_each_pci_dev_iov_resource for_each_pci_dev_bridge_resource for_each_pci_dev_addon_resource Ram's adds: for_each_resource for_each_std_resource for_each_std_and_rom_resource for_each_sriov_resource for_each_bridge_resource It seems like we have a combinatorial explosion of iterators based on various orthogonal selectors (base, rom, iov, bridge window). That doesn't seem understandable or maintainable to me. I wonder if we could get by with *one* iterator, and select the resources of interest either by supplying a bitmask of things we care about, or by doing similar filtering in the caller. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
