On Dec 07 2015 10:52, Takashi Sakamoto wrote:
Hi,
On Dec 07 2015 10:37, Jonathan Woithe wrote:
On Mon, Dec 07, 2015 at 10:27:08AM +0900, Takashi Sakamoto wrote:
On Dec 07 2015 06:57, Jonathan Woithe wrote:
On Sun, Dec 06, 2015 at 10:23:41PM +0900, Takashi Sakamoto wrote:
Unfortunately, ffado library can disturb this functionality.
In RME::Device::init_hardware() function, the library sends a write
transaction
to 0x0000801003f4 with invalid value as higher part of address in
IEEE 1212 or
ISO/IEC 13213. This is a worst case I describe in patch 03.
The number which FFADO writes to this register is not invalid: it is
in fact
the same number which is used in drivers on other operating systems
(obtained from protocol analysis).
No.
As long as I tested with a debug option to firewire-ohci module, it
sends
write transaction with '01000000'. This value includes invalid node ID.
Curious. Fair enough (although I was confused by the reference to the
"higher part" in the commit message: it implied the higher part of the
address in my mind, but in fact the issue with the node ID relates to the
lower part. Whatever. I'll look into it at some point.
In IEEE 1212 (or ISO/IEC 13213), 64 bit addressing is defined. IEEE 1394
utilize the specification.
Here is a actual example of the 64 bit address:
* FFC1'FFFF'F000'0904 (oPCR[0] in node FFC1)
* FFC2'FFFE'0000'0000 (the first address of Private space in node FFC2)
* FFC3'ECC0'8000'0000 (the address of Echo Fireworks Command in node
FFC3)
I mean the 'higher part' is 4 byte in MSB of the address. Drivers
register the 4 byte to 0x'0000'8010'03f4, then Fireface 400 transfers
asynchronous transactions to an address including the 4 byte in its MSB.
More explaination.
If OHCI 1394 host controller gets node ID of FFC7 on the IEEE 1394 bus
and ALSA Fireface driver allocates local address of 0x'4567'0000'0000 of
the controller, then the driver must register the value of '0xFFC74567'
to Fireface 400.
Actually, for Fireface 400, the value should be aligned to little
endiann. Therefore, the driver sends write transaction with value of
'0x6745C7FF'.
In my understanding, 0x0000 for node ID is invalid. Furthermore, 0x0010
is not always true because the address range which drivers allocate on
the controller is different depending on situation.
Regards
Takashi Sakamoto
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