Other Parts Discussed in Thread: XIO2213B
Tool/software: Linux
We seem to have run into a limitation on isochronous data reception using the firewire card with the TI chipset. Although the Linux driver reports that this card has 8 IR contexts, we are seeing data loss when we try to use more than 4 of them simultaneously. We did not see this problem with the old card.
I found a link to a datasheet for the chipset here: http://www.ti.com/product/XIO2213A/technicaldocuments
- The datasheet doesn't indicate how many IR contexts are supported. Can you tell us how many IR contexts are supported by this board? Linux uses the OHCI standard way of querying contexts (writing 0xFFFFFFFF to the ISO receive mask register and then reading it back), but perhaps this chipset/board isn't reporting properly.
- Are the IR and IT contexts independent, or do they share resources? In other words, can we theoretically receive on all of the available IR contexts while simultaneously transmitting using all available IT contexts?
- I saw something concerning in the datasheet, section 2.1 (page 14):
The XIO2213A simultaneously supports up to four posted write transactions, four non-posted transactions, and four completion transactions pending in each direction at any time. Each posted write data queue and completion data queue can store up to 8K bytes of data. The non-posted data queues can store up to 128 bytes of data.
Is this referring to PCI or 1394 transactions? And would these limits (4 transactions, 8K of posted/completed, 128 bytes of non-posted) have an effect on the number of isochronous contexts we could use simultaneously?
Our design requires 6 IR and 2 IT contexts as a minimum, even though the OHCI spec apparently only requires 4/4 as a minimum.