Hi Florian,
On Mon, Aug 04, 2014 at 03:54:49PM -0700, Florian Fainelli wrote:
> Hi Markos,
>
> On 07/18/2014 02:51 AM, Markos Chandras wrote:
> > Different cores use different CCA values to achieve write-combine
> > memory writes. For cores that do not support write-combine we
> > set the default value to CCA:2 (uncached, non-coherent) which is the
> > default value as set by the kernel.
> >
> > Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
> > ---
> [snip]
> break;
> > @@ -765,67 +767,83 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu)
> >
> > static inline void cpu_probe_mips(struct cpuinfo_mips *c, unsigned int cpu)
> > {
> > + c->writecombine = _CACHE_UNCACHED_ACCELERATED;
>
> Why do we set this writecombine setting by default, when later we are
> going to override writecombine on a per-cpu basic.
>
> In the end, we have the following:
>
> cpu_probe()
> c->writecombine = _CACHE_UNCACHED;
>
> cpu_probe_mips()
> c->writecombine = _CACHE_UNCACHED_ACCELERATED:
> ... per-cpu case ...
> c->writecombine = _CACHE_UNCACHED;
>
> Can't we just eliminate the various assignments in cpu_probe_mips() and
> only override c->writecombine if _CACHE_UNCACHED is not suitable?
>
The reason I did it like this, is that new cores (eg *Aptiv family) will use
_CACHE_UNCACHED_ACCELERATED and that's why it's the 'default' option for
the MIPS cores. _CACHE_UNCACHED is only suitable for old cores.
The way it is right now, allows us to not have to set this option whenever we
add support for a new core since it will inherit the default option.
--
markos
