Re: Order of dvb devices

[Andreas Besse <besse@motama.com>]

Devin Heitmueller wrote:
> On Thu, Jan 14, 2010 at 10:35 AM, Andreas Besse <besse@motama.com> wrote:
>   
>> if a system contains multiple DVB cards of the same type, how is the
>> order of devices determined by the driver/kernel?
>>
>> I use 2 Technotrend S2-3200 cards in a system and observerd that if I
>> load the driver driver budget_ci manually as follows:
>>
>> modprobe budget_ci adapter_nr=0,1
>>
>> the device with the lower pci ID 0000:08:00.0 is assigned to adapter0 and the device with the higher pci ID 0000:08:01.0
>> is assigned to adapter1:
>>
>>
>> udevinfo -a -p $(udevinfo -q path -n /dev/dvb/adapter0/frontend0)
>> [...]
>>  looking at parent device '/devices/pci0000:00/0000:00:1e.0/0000:08:00.0':
>>    KERNELS=="0000:08:00.0"
>>    SUBSYSTEMS=="pci"
>>
>>
>> udevinfo -a -p $(udevinfo -q path -n /dev/dvb/adapter1/frontend0)
>> [...]
>>  looking at parent device '/devices/pci0000:00/0000:00:1e.0/0000:08:01.0':
>>    KERNELS=="0000:08:01.0"
>>    SUBSYSTEMS=="pci"
>>
>>
>> Is it true for all DVB drives that the device with the lower PCI id gets the lower adapter name?
>>     
>
> No, you cannot really make this assumption.  In fact, there are users
> who see behavior where uses have two of the same card and the cards
> get flipped around randomly just by rebooting.  The ordering is based
> on the timing of the device driver loading, so it is not
> deterministic.
>   
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?