Am Dienstag, den 17.07.2012, 09:17 +0200 schrieb Carl-Daniel Hailfinger:
Second patch in the series. Error checking has not changed at all, and I intend to fix that in a second spin of this patch. Right now I just want to check if we're on the same page.
Signed-off-by: Carl-Daniel Hailfinger c-d.hailfinger.devel.2006@gmx.net
-struct pci_dev *pcidev_dev = NULL;
Yeah!
if ((addr = pcidev_readbar(dev, bar)) != 0) {
curaddr = addr;pcidev_dev = dev;
found_dev = dev; found++; }
I wonder what to do about this: While the goal of my suggestion was to decouple BAR access from the PCI device scan, it is an integral part of the scan loop, probably to avoid disabled chips (e.g. for onboard components that are not used). The nice property of the code as-is is that you can be sure reading the "primary" BAR will not fail.
As we sometimes need two BARs, having one valid BAR does not mean the device is necessarily usable for us, so this check is only half of what we need. As already discussed on IRC, passing a set of BARs into this function is not really the direction we want to head to, so client code needs to be prepared to find unusable BARs anyway. Still, we like autoskip. Several ideas come to my mind - Use the PCI command word for autoskip - Implement a set-of-BAR (bitmask, array) anyway - Probe that all BARs (except ROM perhaps) that are not unused contain sensible values - Hand in a "is_usable" callback (a standard callback for testing a single BAR could be provided)
All of these approaches of course complicate pcidev_init, but it seems like the only choices we have is: - do the BAR check the right way (TM) - loose the autoskip of disabled PCI devices
Regards, Michael Karcher