[U-Boot] [PATCH v9 2/2] Odroid-XU3: Add documentation for Odroid-XU3

[Simon Glass]

Hi,

On 8 December 2014 at 18:27, Kevin Hilman <khilman at kernel.org> wrote:
>
> Hi Simon,
>
> Simon Glass <sjg at chromium.org> writes:
>
> > On 8 December 2014 at 10:58, Kevin Hilman <khilman at kernel.org> wrote:
>
> [...]
>
> >> FWIW, the XU3 firmware is broken in other ways as well which have a
> >> major impact on power management.
> >>
> >> First, with mainline kernels using MCPM, only 6 of 8 CPUs come
> >> online.  However, even with that fixed[1], it turns out that the kernel
> >> can't properly manage CCI due to secure firmware[2], which means that MCPM
> >> (multi-cluster power management) can't work, and thus the low-power
> >> cluster-idle states can't work, the big.LITTLE switcher cannot work, and
> >> the ongoing work on energy-aware scheduling will not be useful on this
> >> platform.
> >>
> >> Anyone know what are the chances of getting a non-secure version of the
> >> firmware for this platform.  The Samsung Chromebook2 with basically the
> >> same SoC (5800 compared to the 5422 on the XU3) ships with non-secure
> >> firmware so all of the above mentioned features are working just fine.
> >
> > I have pushed on this but apparently it is not possible - they need to
> > sign every BL2. The only implementation I've seen sets up the chip in
> > BL2 (U-Boot SPL) so I don't think we can work around it.
>
> Not quite sure I'm following...
>
> So is secure-mode enabled before BL2 is started?  Or do you mean BL2 is
> where secure-mode is enabled?  If it's done in BL2, and if the
> hardkernel folks are willing to sign BL2 images (which I gathered from
> discussions elsewhere in this series) then it seems possible to turn off
> secure-mode.


Yes it is possible - and easy - to do in BL2 / U-Boot SPL. This is
what the Chromebooks do.

>
>
> So I went to look in the u-boot-samsung repo and didn't see the code for
> the SPL there.  Is the BL2 source (which I understood to be u-boot SPL)
> in some other repo?


It's in mainline U-Boot so no particular need to go to the Samsung
tree. See arch/arm/cpu/armv7/exynos/spl_boot.c and tzpc.c for the
TrustZone stuff.

>
> > It takes us back to the 1960s where we sent off our code at night to
> > run it :-)
> >
> > I think the best bet is the current effort to mainline the rest of the
> > Chromebook code then try to build it for XU3.
>
> What's the status of that effort?

Coming along but the big/little support is still not there. The
display works and most core peripherals. Needs more SPL work.

>
>
> >>
> >> I'm working on getting these same features working on the XU3, but this
> >> broken firmware as brought a halt to any real progress.
> >
> > Agreed, but I think this is feasible once U-Boot on XU3 is sorted out.
>
> Let's hope so.
>
> Kevin
>

Regards,
Simon