On Wed, Aug 10, 2011 at 01:50:17PM +0100, Martyn Welch wrote: > On 10/08/11 11:41, Manohar Vanga wrote: > > Hey Martyn, > > > >> I'm sorry, I'm still simply not convinced by this patch: > >> > >> 1) For a single bus driver (i.e. in the situation where we have 2 bridges of > >> the same type), the numbering of the buses is still dependent on the order > >> that they are found in the scan. > > > > Yes this is still a bug. But this patch doesn't address this case. > > > >> 2) If the bridge drivers are loaded as modules, I have a feeling they will be > >> loaded sequentially and therefore the order of the bridges would only change > >> if the order of the loading of the drivers changed. > > > > And this is a major problem when it comes to multiple bridges of differing > > types. What I'm saying is that this patch simply fixes this one problematic > > case. We can move this out as soon as we have a more robust implementation. > > > > As of now however, I think applying this is useful as we have a decent > > workaround to the problem. If you want I can make the fact of it being > > applicable only to cases with differing bridges explicit in the commit > > message. > > > > The problem is, I'm not convinced that this is the correct approach to take. I > think this should be parsed from sysfs dynamically (which may require some > work). I shall use the ethernet devices on my machine as an example: > > I have 2 ethernet devices (and lo) on my machine: > > $ ls /sys/class/net/ > eth0 eth1 lo > $ > > These are symlinks and I can quite quickly find out which each of these > devices in (based on topology): > $ ls -l /sys/class/net/ > total 0 > lrwxrwxrwx 1 root root 0 2011-08-10 11:56 eth0 -> > ../../devices/pci0000:00/0000:00:19.0/net/eth0 > lrwxrwxrwx 1 root root 0 2011-08-10 11:56 eth1 -> > ../../devices/pci0000:00/0000:00:1c.1/0000:03:00.0/net/eth1 > lrwxrwxrwx 1 root root 0 2011-08-10 11:56 lo -> ../../devices/virtual/net/lo > $ > > I'd think that this contains the information that you have in the config file > (based on the previous discussion we had) and would allow you to map the bus > numbering after booting. > > To do this, I think we need to register a class called "vme", I guess in > vme_init() and add a call to class_device_register in vme_register_bridge and > a call to class_device_unregister in vme_unregister_bridge. > > Greg: Is that right? Yes. > I'm really not convinced that the solution presented in this patch is suitable > for inclusion upstream. I agree. Bus numbers are dynamic and should NEVER be depended on by userspace to be static and unchanging on reboots. thanks, greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
