On Sat, Jan 16, 2010 at 3:00 AM, Oliver Endriss <o.endriss@xxxxxx> wrote: > Devin Heitmueller wrote: >> On Thu, Jan 14, 2010 at 11:01 AM, Andreas Besse <besse@xxxxxxxxxx> wrote: >> > yes if there are different drivers I already observed the behaviour that >> > the ordering gets flipped after reboot. >> > >> > But if I assume, that there is only *one* driver that is loaded (e.g. >> > budget_av) for all dvb cards in the system, how is the ordering of these >> > devices determined? How does the driver "search" for available dvb cards? > > The driver does not 'search' for a card. The driver registers the ids of > all supported cards with the pci subsystem of the kernel. > > When the pci subsystem detects a new card, it calls the 'probe' routine > of the driver (for example saa7146_init_one for saa7146-based cards). > So the ordering is determined by the pci subsystem. > >> I believe your assumption is incorrect. I believe the enumeration >> order is not deterministic even for multiple instances of the same >> driver. It is not uncommon to hear mythtv users complain that "I have >> two PVR-150 cards installed in my PC and the order sometimes get >> reversed on reboot". > > Afaik the indeterministic behaviour is caused by udev, not by the > kernel. We never had these problems before udev was introduced. True, the ordering is not exactly the same everytime. One will need to provide PCI Bus related info also to a practical udev configuration to get things sorted out in a sane way, rather than anything else. Regards, Manu -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
