Openmoko Bug #2215: distros using fso-gsm0710muxd will not register

[Openmoko Public Trac]

#2215: distros using fso-gsm0710muxd will not register
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 Reporter:  BillK            |          Owner:  openmoko-kernel      
     Type:  defect           |         Status:  new                  
 Priority:  normal           |      Milestone:  FSO                  
Component:  System Software  |        Version:                       
 Severity:  normal           |       Keywords:  gsm0710muxd GSM modem
 Haspatch:  0                |      Blockedby:                       
Estimated:                   |    Patchreview:                       
 Blocking:                   |   Reproducible:  always               
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Comment(by BillK):

 ok, found the difference, but needs a serial guru to make sense of it:)

 I straced qtopia (working) and the mux (not working) and found that there
 is a difference in the termio c_cflags used.
 qtopia: c_cflags=0x18b2
 mux: c_cflags=0x800018b2

 According to "bits/termio.h" (if I have decoded it right) the mux is
 setting CRTSCTS flowcontrol.
 However, this is again set a couple of lines later using an IOCTL.  qtopia
 only sets CRTSCTS using the IOCTL.

 if I use stty to force it off, the repeating " AT COMMAND READY" messages
 stop, and I can again communicate with the modem via minicom etc.  If the
 bit is set, all I get are the messages.

 The weirdest part is that after it uses the ioctl, qtopia appears to have
 reset the uart to 0x800018b2 (which is actually what I expect), and keeps
 working.

 I have not been able to get the mux to behave this way so far, however I
 can cure the "AT COMM..." messages by just turning CRTSCTS off using the
 "stty" command.

 BillK

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Ticket URL: <https://docs.openmoko.org/trac/ticket/2215#comment:2>
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