PCI: Remove pci_enable_device_bars() from documentation

Patch below removes pci_enable_device_bars() from Documentation/pci.txt .

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>


authored by Grant Grundler and committed by Greg Kroah-Hartman d48b5d3a 7cbe5b60

+1 -36
+1 -36
Documentation/pci.txt
··· 274 274 o allocate an IRQ (if BIOS did not). 275 275 276 276 NOTE: pci_enable_device() can fail! Check the return value. 277 - NOTE2: Also see pci_enable_device_bars() below. Drivers can 278 - attempt to enable only a subset of BARs they need. 279 277 280 278 [ OS BUG: we don't check resource allocations before enabling those 281 279 resources. The sequence would make more sense if we called ··· 603 605 604 606 605 607 606 - 10. pci_enable_device_bars() and Legacy I/O Port space 607 - ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 608 - 609 - Large servers may not be able to provide I/O port resources to all PCI 610 - devices. I/O Port space is only 64KB on Intel Architecture[1] and is 611 - likely also fragmented since the I/O base register of PCI-to-PCI 612 - bridge will usually be aligned to a 4KB boundary[2]. On such systems, 613 - pci_enable_device() and pci_request_region() will fail when 614 - attempting to enable I/O Port regions that don't have I/O Port 615 - resources assigned. 616 - 617 - Fortunately, many PCI devices which request I/O Port resources also 618 - provide access to the same registers via MMIO BARs. These devices can 619 - be handled without using I/O port space and the drivers typically 620 - offer a CONFIG_ option to only use MMIO regions 621 - (e.g. CONFIG_TULIP_MMIO). PCI devices typically provide I/O port 622 - interface for legacy OSes and will work when I/O port resources are not 623 - assigned. The "PCI Local Bus Specification Revision 3.0" discusses 624 - this on p.44, "IMPLEMENTATION NOTE". 625 - 626 - If your PCI device driver doesn't need I/O port resources assigned to 627 - I/O Port BARs, you should use pci_enable_device_bars() instead of 628 - pci_enable_device() in order not to enable I/O port regions for the 629 - corresponding devices. In addition, you should use 630 - pci_request_selected_regions() and pci_release_selected_regions() 631 - instead of pci_request_regions()/pci_release_regions() in order not to 632 - request/release I/O port regions for the corresponding devices. 633 - 634 - [1] Some systems support 64KB I/O port space per PCI segment. 635 - [2] Some PCI-to-PCI bridges support optional 1KB aligned I/O base. 636 - 637 - 638 - 639 - 11. MMIO Space and "Write Posting" 608 + 10. MMIO Space and "Write Posting" 640 609 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 641 610 642 611 Converting a driver from using I/O Port space to using MMIO space