>>>>> "Hendrik" == Hendrik <chasake@xxxxxxxxx> writes:
Hendrik> Hello Uwe, Hi, I am currently porting our software from Windows
Hendrik> (using FTDI's own driver) to Linux (using libftdi). Thus far it
Hendrik> works great but I am now on a specific case in the program that
Hendrik> needs to read chunks of data from our device. The commands
Hendrik> between the host (now a PC, later an embedded ...
>> No answer to your questions but another questions from my side: - Why
>> are you useing libftdi and not the kernel driver ftdi_sio?
Hendrik> I am using the libftdi ftdi_read function and have unloaded the
Hendrik> ftdi_sio kernel module. I also updated to libftdi 1.2 today but
Hendrik> the same problem occurred on 1.1 (I updated today because I
Hendrik> wanted to know if the problem went away with this version but
Hendrik> it didn't).
This doesn't tell _why_ you don't use the kernel driver...
I think the kernel driver is better in such corner cases.
>> - Did you try asynchronous transfers (ftdi_read_data_submit)?
Hendrik> No, I try/tried to stay away from async transfers as the whole
Hendrik> protocol is request->reply based which makes it easier to
Hendrik> program (and easier to read what's going on).
The code flow isn't that different.
Without aync transfer:
'ftdi_write' the request
while (not all 522 bytes received)
'ftdi_read' the reply
With async transfer:
'ftdi_read_data_submit' setup the read request
'ftdi_write' the request
while(read transfer not complete) wait;
Hendrik> I looked through the libftdi sources but can you tell me what
Hendrik> the latency timer actually does (in combination with the read
Hendrik> chunk size)? I know its function and that a read command will
Hendrik> return when the timer has expired and the chunk was not
Hendrik> competely read, but where is this information stored? The
Hendrik> ftdI_read_data function don't seem to use the timer so it must
Hendrik> be hardware based, but if the FTDI buffer itself is not as
Hendrik> large as the 4KB chunk, where is this data buffered then in
Hendrik> combination with the timer?
Hendrik> I will post some more debugging info tomorrow.
Either way, the libftdi problem needs to be solved, so thanks for your
patience.
Bye
--
Uwe Bonnes bon@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
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