stable connection of nokia 3220 via CA42 cable is possible

[Burkhard Soehne]

With the appended patch of "common/links/fbus.c" to the last released version 
0.6.19 of gnokii I want to show that it is possible to establish a stable 
connection of a nokia3220 via CA42 cable.

This patch IS NOT a proper solution, it is actually a workaround. It should 
give a motivation of starting a discussion how to fix the problems.

Mainly I have changed the handling of the sequence-id.
For my nokia3220 the sequence-id should not start at zero for every gnokii 
command. It should set to zero only after booting the mobile.
The next expected sequence-id will be written and read in "/tmp/seq.dat".

Without this patch the connection to my nokia3220 will break mostly after the 
second gnokii command.
The first command works fine.
The second command produces "Received Ack of type xx, seq: 80" and later ..." 
seq: 81" and then works fine.
The third command always produces errors.
(The "seq: 8x" seem to identify a sequence error, which is ignored in the 
released version.)

It seem to be NOT a question of mobile-hardware or (clone-)cable-hardware to 
establish a stable connection, it is only a question of software.
There must be different firmware versions for the transmission over FBUS2. My 
nokia7360 will work fine with the released version of gnokii, but perhaps 
older mobiles (at least my 3220) have a different behaviour. Perhaps we can 
add this in a reference list.

To run my patch, please delete "/tmp/seq.dat" whenever you boot your mobile. 
Please boot the mobile before the first start of gnokii. After this you can 
run gnokii commands for many times.

This synchronization is exactly the problem for a proper bugfix. How can 
gnokii find out which sequence id the mobile expects?

1. Is there a way to check the sequence id?
2. Is there a way to reset the sequence id?
3. Should gnokii always send exactly 8 requests (or a multiple of 8), because 
the sequence id always counts between 0 and 7?
4. Do we need a deamon, which holds the connection all the time?
5. Are there any other suggestions?

Sometimes I have to reset mobile and "/tmp/seq.dat". I guess this is after a 
transmission error. Sometimes gnokii can recover itself, sometimes not. This 
happens after 5 to 200 commands on ubuntu. Under MinGW I have seen no 
transmission error.

The changes in send_command() are to provide an infinite loop in the beginning 
of the very first command.

I look forward to the discussion.

Hardi

fbus.patch
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