Hi Yann,
On Mon, Dec 17, 2012 at 3:12 PM, Yann Droneaud <ydrone...@opteya.com> wrote: > Le lundi 17 décembre 2012 à 12:41 +0530, Ritesh Harjani a écrit : > > Hi Everyone, > > > > When this command (at+cfun=1,1) is executed on phone, it does a > > reboot. I want to know which and how this command calls the kernel > > level functions. > > I googled this, but seems like all the data explains only about AT > > command and not as to how this reboot process is done. > > > > The kernel alone is not responsible of interpreting Hayes commands (AT). > > According to ETSI TS 100 916 V7.4.0 (1999-11) Technical Specification > Digital cellular telecommunications system (Phase 2+); AT command set > for GSM Mobile Equipment (ME) (GSM 07.07 version 7.4.0 Release 1998), > Section 8.2 Set phone functionality +CFUN (found through by > http://wiki.openmoko.org/wiki/Hardware:AT_Commands ), this command > (AT+CFUN=1,1) is one of the command a "baseband" must implement. > > >And this command is asking for a reboot. So what you describe seems more > >likely to be a hardware problem. > On Android phones(some of them) there are essentially two processors. The *Application Processor (AP)* where your Android operating system (AOS) and user interface (UI) lives, and the *Baseband/Cellular Processor (BP/CP)* where all the GSM and other high-tech communication magic happens, including the modem we wish to communicate with. Here, AP and BP communicates via UART (serial line), USB, SPI or through shared RAM and/or a combination of these. Therefore there will always be some path directly accessible from the outside that we should be able to use to communicate directly with the BP. So, what I am asking for is not any hardware problem. What I have figured out that, this command (at+cun=1,1) calls for sysrq reset which does a emergency restart. But, I wanted to know the exact path that it follows before calling Sysrq key. Thank you Ritesh > > Regards. > > -- > Yann Droneaud > OPTEYA > > >
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