Re: [libdc] Marlin on 12.2 follow up

[Stefan R. <st...@s5...>]

On Oct 17 E Chalaron wrote:
> Using Physical ID 0
> Using  0xFFFFF0000018  as Mem. Offset
> Result : 0x00000000
> 
> Using Physical ID 0
> Using  0xFFFFF000001c  as Mem. Offset
> Result : 0x19000000
> 
> not understanding the results as such I am a bit stuck.

Read it from destination ID 1, not 0.  In this session, the camera had the
physical ID 0 and the Linux node certainly 1.  The Linux firewire-core
determines whether an outbound split transaction timed out based on its
*own* Split_Timeout register.

[...]
> Error while reading from IEEE1394: : Resource temporarily unavailable
> 0/0x0000fffff0000400: read failed
> 0/0x0000fffff0000400: wrong bus info block length
> Error while reading from IEEE1394: : Resource temporarily unavailable
> 0/0x0000fffff0000400: read failed
> 0/0x0000fffff0000400: wrong bus info block length
> Error while reading from IEEE1394: : Resource temporarily unavailable
> 0/0x0000fffff0000400: read failed
> 0/0x0000fffff0000400: wrong bus info block length
> 
> So bus reset ...

AFAIR this could be bus resets or it could be something else
(camera sending back ack-busy, perhaps).  If you run as root
# echo 2 > /sys/module/firewire_ohci/parameters/debug
you get kernel messages from every self-ID-complete event (which is an
event that concludes a bus reset event or a burst of bus reset events).

With
# echo 3 > /sys/module/firewire_ohci/parameters/debug
you additionally get messages from each outbound and inbound transaction.
This would for example show when we get ack-busy from a camera.  A normal
split transaction consists of:
A -> B: request 
B -> A: ack-pending
B -> A: response
A -> B: ack-complete
There are other transaction types though.

By the way:  You wrote earlier that you had a v2.0.7 based libraw1394
package installed.  Libraw1394 v2.0.8 and later carry one optimization:
If a libraw1394 based application attempts to read a node's
Configuration_ROM register (a 1024 kB large register starting at
0xfffff0000400, see gscanbus's log above), then libraw1394 will return
data from the kernel's Configuration_ROM cache instead of bothering the
node.  This optimization only concerns Configuration_ROM, not any other
register.

(The latest stable release of libraw1394 is v2.1.0; the last strictly
bug-fix-only release was v2.0.9.  Any distribution which is actively
maintained should upgrade to v2.1.0, or at the very least to v2.0.9.)
-- 
Stefan Richter
-=====-===-- =-=- =---=
http://arcgraph.de/sr/