On Sun, Feb 10, 2013 at 7:38 PM, Len Ovens <len@ovenwerks.net> wrote:

On Sun, February 10, 2013 3:03 pm, Paul Davis wrote:
> On Sun, Feb 10, 2013 at 5:58 PM, Len Ovens <len@ovenwerks.net> wrote:
>
>>
>>
>> Two linux drivers to consider. The PCIe stuff in the kernel is probably
>> optimized for throughput to make the best use of Video cards, fast ether
>> net, etc. Means larger chunks of data for less overhead. Maybe higher
>> latency too. It shouldn't be as it is faster than PCI which handled
>> things
>> just fine. The extra throughput should actually help for higher channel
>> counts. (from reading though some of the docs on netjack)
>>
>
> not really. the drivers for RME devices are PCI-species independent. the
> PCI bus doesn't really exist for them, which is why the same driver can
> interact with the (old) cardbus version as if it is directly on the bus.
> drivers see address spaces and registers, not the bus.

Ok, so what I get from this is that the CPU sees a PCIe device in the same
way it sees a PCI device. Yet I know from reading the specs on both the
PCI to PCIe bridge and the MB chip sets, that there is some firmware
involved at both ends.

that would likely be in the chipset that interacts with the bus. device drivers for particular PCI(.) devices do not interact with this level of hardware (in general).
 
This may not be something that is run by the CPU
itself (though it could be) but something that could be run by another
processor in the glue logic itself. It may rather be part of the bios. I
don't know. Most of the PCI(e) sound cards have a DSP with some sort of
firmware as well.

RME devices do not. they use Xilinx FPGA chips. the firmware (the actual firmware) is on an eprom that is surface mounted.

personally, i consider audio interfaces with onboard DSP to be a mostly-bad design. if i wanted DSP, i'd buy some kind of processor for that. i don't want a decade old DSP chip cluttering up my audio interface - my hammerfall cards are now 13 years old and still working perfectly, unaffected by the fact that DSP technology has moved on.
 
How much all of this interacts I don't know. What I do
see is a lot of brand new MBs that handle sound badly.

i don't know of any MBs that in and of themselves handle sound badly (these days, anyway). the problems come from a different set of levels (a few notes on this (to be expanded): http://manual.ardour.org/setting-up-your-system/the-right-computer-system-for-digital-audio/


 

--
Len Ovens
www.OvenWerks.net