[PATCH] ARM: shmobile: Check r8a7791 MD21 at SMP boot

[Simon Horman]

On Thu, Feb 27, 2014 at 09:08:06AM +0100, Geert Uytterhoeven wrote:
> Hi Magnus,
> 
> On Thu, Feb 27, 2014 at 4:33 AM, Magnus Damm <magnus.damm at gmail.com> wrote:
> >>>  This is a reworked version of the APMU patch previously posted as
> >>>  [PATCH] ARM: shmobile: Check MD21 at SMP boot in case of APMU
> >>
> >> Your previous version also affected r8a7790/Lager.
> >> Isn't this check no longer needed there? According to the Lager manual,
> >> MD21 also enables hardware debug mode, and is also controlled by
> >> SW8-4. Of course the CPU may behave differently, as the CPU cores
> >> are different.
> >
> > Yes, you are correct that the previous version of the patch also
> > affected Lager. And that both r8a7790 and r8a7791 mention the MD21 bit
> > together with JTAG debugging.
> >
> > I recently used the patch on Lager and I discovered that I apparently
> > had been running with MD21 on my Lager since forever, and surprisingly
> > it worked regardless. Since there is no documentation on r8a7790 or
> > r8a7791 I simply decided to handle them separately and only enable
> > where it is needed.
> 
> You could have been lucky?
> 
> On Koelsch, I only had failures after Real Cold Boot, i.e. on boot up in the
> morning. And not always, so there could be a timing issue involved.
> 
> > I've also been told that it is possible to allow SMP operation
> > together with JTAG, apparently some magic with RST is needed. It seems
> > that the power domains are treated differently depending on the MD21
> > setting. Not sure if this applies to both r8a7790 and r8a7791, but if
> > we end up with similar fixes we can consolidate. Until then I think
> > dealing with them one by one makes sense.
> 
> Furthermore, I haven't seen any SPI timeouts after I disabled MD21 (holding
> wood, and rabbit legs ;-). So the SMP memory (in)coherency I saw there
> could have been caused by a wobbly SMP setup.

Hi Magnus,

I am a little confused about the status of this patch?
Would you like me to queue it up?