Boot hang regression 3.10.0-rc4 -> 3.10.0

[Bedia, Vaibhav]

On Thu, Jul 04, 2013 at 21:30:14, Mark Jackson wrote:
> On 04/07/13 16:14, Mark Jackson wrote:
> > On 04/07/13 14:25, Mark Jackson wrote:
> >> Our custom AM335x board has been booting just fine under 3.10.0-rc4.
> >>
> >> I've just done a git pull to update to 3.10 (now that it's released)
> >> and the board now hangs.
> >>
> >> Before I start trying to bisect the issue, does anyone have an clues ?
> > 
> > Okay ... I've now bisected it to:-
> > 
> > a630fbfbb1beeffc5bbe542a7986bf2068874633 is the first bad commit
> > commit a630fbfbb1beeffc5bbe542a7986bf2068874633
> > Author: Tony Lindgren <tony at atomide.com>
> > Date:   Mon Jun 10 07:39:09 2013 -0700
> > 
> >     serial: omap: Fix device tree based PM runtime
> 
> However, reverting the commit does *not* fix the issue, weird !!
> 
> But I have now tested:-
> 
> v3.10-rc4     -> works
> v3.10-rc5     -> works
> v3.10-rc6     -> works
> v3.10-rc7     -> works
> v3.10         -> works
> origin/master -> hangs
> 
> Any ideas ?

I just checked the behavior on my AM335x-EVM. Current mainline boots fine
provided I don't use earlyprintk.  The offending patch [1] in this case is the one
that tries to get rid of omap_serial_early_init() for DT boot. This change inadvertently
also results in the console UART getting reset and idled during bootup and that's where
the boot stops for you. I think if you skip earlyprintk from the bootargs you should see
the system booting fine. 

I guess we need to retain the NO_IDLE and NO_RESET aspect for the console UART in
omap_serial_early_init() to get earlyprintk working again.

Regards,
Vaibhav B.

[1] http://www.spinics.net/lists/linux-omap/msg91825.html