Re: [PATCH 5/5] arm: msm: smd: fix SMD modem processor sync condition

[Daniel Walker <dwalker@codeaurora.org>]

On Mon, 2010-04-19 at 12:06 -0700, Dima Zavin wrote:
> On Mon, Apr 19, 2010 at 12:01 PM, Daniel Walker <dwalker@codeaurora.org> wrote:
> > On Mon, 2010-04-19 at 11:34 -0700, Dima Zavin wrote:
> >> Do we really need a formalized blocking point here? The apps processor
> >> can do other useful initialization work while the modem is booting.
> >> The first time you do a proc_comm call, it checks the PCOM_READY
> >> state, and will block anyway. Preventing the apps processor from
> >> continuing until then is suboptimal. If there are bugs in the modem
> >> code where it incorrectly stomps on shared resources, then those
> >> should be fixed. This patch looks like a hack to me.
> >
> >
> > Yes, we need to formalize a blocking point .. The apps processor waits
> > in this way no matter what you do .. Like your saying above "The first
> > time you do a proc_comm call, it checks the PCOM_READY state, and will
> > block anyway" that's a hack .. What your saying is _maybe_ there exists
> > a proc_comm call early enough to prevent a crash, or maybe not .. That's
> > not formal enough.
> 
> That's not at all what I am saying. There's no maybe. If I don't need
> anything from the modem, I won't make a proc_comm call. If there is a
> crash because the modem is modifying shared resources that affect the
> apps processor without an appropriate synchronization point, then it's
> a bug on the modem side. Making this change will only mask modem bugs.

If you don't make a proc_call call SMD won't initialize properly early
on, since the modem may or may not be booted far enough to accept input
over SMD.. Then you can basically have a failed SMD init, which means
you crash when you actually need stuff through SMD.

Daniel