[U-Boot] [PATCH] riscv: cpu: Skip unavailable hart in the get_count() op

[Bin Meng]

Hi Lukas,

On Thu, Aug 8, 2019 at 10:03 PM Auer, Lukas
<lukas.auer at aisec.fraunhofer.de> wrote:
>
> Hi Bin,
>
> On Thu, 2019-08-08 at 21:25 +0800, Bin Meng wrote:
> > Hi Lukas,
> >
> > On Thu, Aug 8, 2019 at 7:22 PM Auer, Lukas
> > <lukas.auer at aisec.fraunhofer.de> wrote:
> > > Hi Bin,
> > >
> > > On Thu, 2019-08-08 at 00:52 -0700, Bin Meng wrote:
> > > > We should not count in hart that is marked as not available in the
> > > > device tree in riscv_cpu_get_count().
> > > >
> > >
> > > I think it might make sense to also exclude harts that are not listed
> > > as available in the available_harts mask. So the same logic as in
> > > arch/riscv/lib/smp.c. In this case, the bind function should probably
> > > check the mask as well.
> > >
> >
> > Yes, the check to available_harts mask can be added in
> > riscv_cpu_get_count(). I will do that.
> >
> > However, I doubt we could do available_harts mask check in the bind
> > function. If it returns error for non-available harts, the whole
> > initialization process fails.
> >
>
> You are right, I did not think about that. Perhaps it's best to ignore
> the available_harts mask in the count function as well then.
>

Agreed. I will leave this patch as it is.

> It just checked where cpu_get_count() is used. The Andes PLIC driver
> (lib/andes_plic.c) uses it in a way that the patch might break the
> driver. It iterates over all harts, assuming the first hart is 0 and
> the last hart the result of cpu_get_count(). If any of the harts is set
> to disabled, this will no longer be true. It's probably best to update
> the driver to use the ofnode_for_each_subnode() macro to iterate over
> all harts. Rick, can you update the driver?
>

Good catch!

Regards,
Bin