On Mon, 16 Oct 2006 10:44:30 +1000 Paul Mackerras <[EMAIL PROTECTED]> wrote:
> Andrew Morton writes: > > > Let me restore the words from my earlier email which you removed so that > > you could say that: > > > > For you the driver author to make assumptions about what's happening > > inside pci_set_mwi() is a layering violation. Maybe the bridge got > > hot-unplugged. Maybe the attempt to set MWI caused some synchronous PCI > > error. For example, take a look at the various implementations of > > pci_ops.read() around the place - various of them can fail for various > > reasons. > > Maybe aliens are firing a ray-gun at the card. I think it's > fundamentally wrong for the driver to deny service completely because > of a maybe. > > Either there was a transient error that only affected the attempt to > set MWI, in which case a printk (inside pci_set_mwi!) is appropriate, > and we carry on. Or there is a persistent error condition, in which > case the driver will see something else fail soon enough - something > that the driver actually needs to have working in order to operate - > and fail at that point. > > For the driver to stop and refuse to go any further because of an > error in pci_set_mwi has far more disadvantages than advantages. > Sure. So I think what we're needing in this case is: - A modified version of Willy's patch which returns 0 if MWI was enabled, 1 if MWI isn't available. - A printk if something went bad It appears that the various functions which try to match the line sizes already have printks if something went wrong, but they're using KERN_DEBUG facility level and that warning would dupliate the new one in pci_set_mwi(). And although the various implementations of pci_read_config_foo() and pci_write_config_foo() can return error codes, we have so many instances where we're not checking it, I don't think it's practical to try to start doing that everywhere. - drop the __must_check. Question is, should pci_set_mwi() ever return -EFOO? I guess it should, in the case where setting the line size didn't work out. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
