On 2013-04-10 17:16, H Hartley Sweeten wrote:
On Wednesday, March 06, 2013 4:34 PM, H Hartley Sweeten wrote:Question, when doing an ioremap() of a PCI resource which is more correct? iobase = pci_resource_start(pcidev, bar); len = pci_resource_len(pcidev, bar); mmio = ioremap(iobase, len); or mmio = pci_ioremap_bar(pcidev, bar); pci_ioremap_bar() does some extra sanity checking to make sure the bar is actually a memory resource and then does an ioremap_nocache(). If the ioremap() is in order to talk to the registers on the PCI device wouldn't the pci_ioremap_bar() be more correct?Greg / Ian / Dan, Do you have any ideas/opinions on the question above?
Saves a couple of lines of code, I suppose. The extra sanity makes sense for the function to do for defensive programming reasons, but is not particularly useful for the caller unless there are some (presumably older) variants of a PCI card that match the driver's PCI ID table, but have registers in I/O space instead of memory space (in which case, it's better that pci_ioremap_bar() returns the NULL rather than ioremap_nocache() attempting to remap a port address (though that would probably fail and return NULL anyway).
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