Hi Yann, <br><br><br><div class="gmail_quote">On Mon, Dec 17, 2012 at 3:12 PM, Yann Droneaud <span dir="ltr"><<a href="mailto:ydroneaud@opteya.com" target="_blank">ydroneaud@opteya.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Le lundi 17 décembre 2012 à 12:41 +0530, Ritesh Harjani a écrit :<br>
<div class="im">> Hi Everyone,<br>
><br>
> When this command (at+cfun=1,1) is executed on phone, it does a<br>
> reboot. I want to know which and how this command calls the kernel<br>
> level functions.<br>
> I googled this, but seems like all the data explains only about AT<br>
> command and not as to how this reboot process is done.<br>
><br>
<br>
</div>The kernel alone is not responsible of interpreting Hayes commands (AT).<br>
<br>
According to ETSI TS 100 916 V7.4.0 (1999-11) Technical Specification<br>
Digital cellular telecommunications system (Phase 2+); AT command set<br>
for GSM Mobile Equipment (ME) (GSM 07.07 version 7.4.0 Release 1998),<br>
Section 8.2 Set phone functionality +CFUN (found through by<br>
<a href="http://wiki.openmoko.org/wiki/Hardware:AT_Commands" target="_blank">http://wiki.openmoko.org/wiki/Hardware:AT_Commands</a> ), this command<br>
(AT+CFUN=1,1) is one of the command a "baseband" must implement.<br>
<br>
>And this command is asking for a reboot. So what you describe seems more<br>
>likely to be a hardware problem.<br></blockquote><div><br>On Android phones(some of them) there are essentially two processors. The <i>Application Processor (AP)</i> where your Android operating system (AOS) and user interface (UI) lives, and the <i>Baseband/Cellular Processor (BP/CP)</i>
where all the GSM and other high-tech communication magic happens,
including the modem we wish to communicate with. <br>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. <br><br>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. <br>But, I wanted to know the exact path that it follows before calling Sysrq key. <br>
<br>Thank you<br>Ritesh<br> </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Regards.<br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
Yann Droneaud<br>
OPTEYA<br>
<br>
<br>
</font></span></blockquote></div><br>