interrupt not always generated when flowcontrolled=1 and modem wants to talk

[lindi]

This issue has been discussed on IRC and a mailing list thread
"Occasional fail to initiate resume by incoming call, easy workaround
proposed" but I have not seen a bug report with clear steps to
reproduce. In that thread moko11-beta1 firmware is suggested as a
workaround so anybody who upgrades to that will want to verify that it
really fixes the issue for them with these steps.

Steps to reproduce:
1) start

socat - file:/dev/ttySAC0,crtscts,crnl,echo=0,b115200

in another terminal and keep it running during steps 1-9

2) echo 0 > /sys/class/i2c-adapter/i2c-0/0-0073/neo1973-pm-gsm.0/power_on
3) echo 1 > /sys/class/i2c-adapter/i2c-0/0-0073/neo1973-pm-gsm.0/power_on

4) register to network manually by typing the following to socat (mind
   your own PIN though!):
  
ATE1
AT+CFUN=1
AT+CPIN="0000"
AT+CPIN?
AT+COPS
AT+COPS?

4) grep modem /proc/interrupts
5) call the phone from some other phone
6) let caller hangup
7) echo 1 > /sys/class/i2c-adapter/i2c-0/0-0073/neo1973-pm-gsm.0/flowcontrolled
8) call the phone from some other phone
9) grep modem /proc/interrupts

Expected results:
4-9) When flowcontrolled=1 an interrupt is generated when GSM has something to send.

Actual results:
4-9) Interrupt count does not increase:
17:          5    s3c-ext0  modem
17:          5    s3c-ext0  modem

and thus if the phone is put to suspend it won't wake up either.

More info:
1) I am running moko8 firmware on GTA02V5

AT+CGMR
+CGMR: "HW: GTA02BV5, GSM: gsm_ac_gp_fd_pu_em_cph_ds_vc_cal35_ri_36_amd8_ts0-Moko8"
$ grep Revision /proc/cpuinfo 
Revision        : 0350

2) I am using andy-tracking kernel b8b36e5ec3db71d5 from beginning of January 2009.

[lindi]

I upgraded to

b9ff82c0a3351e1f72ba48aa9ae08c8d  calypso-moko11-beta1.m0
+CGMR: "GSM: gsm_ac_gp_fd_pu_em_cph_ds_vc_cal35_ri_36_amd8_ts0-Moko11b1"

and can verify that now interrupt count increases by one as expected:

root@ginger:~# grep modem /proc/interrupts
 17:          8    s3c-ext0  modem
root@ginger:~# grep modem /proc/interrupts
 17:          9    s3c-ext0  modem

I will continue making automated "resume by call" tests every two hours and let you know if I see anything odd.

[wendy_hung]

This issue could be fix in moko11 GSM firmware. If you face the problem again, please open another ticket for specific case. :)

The flashing detail can be found in this link:
​http://wiki.openmoko.org/wiki/GSM/Flashing

Big thanks for Joerg's big help!