Re: [PATCH 1/1] perf/arm-cmn: Add more bits to child node address offset field

[Ilkka Koskinen]

Will,

Would you need something more or could you pick up this patch?

Cheers, Ilkka

On Tue, 9 Aug 2022, Robin Murphy wrote:
> On 2022-08-08 20:54, Ilkka Koskinen wrote:
> > CMN-600 uses bits [27:0] for child node address offset while bits [30:28]
> > are required to be zero.
> >
> > For CMN-650, the child node address offset field has been increased
> > to include bits [29:0] while leaving only bit 30 set to zero.
> >
> > Let's include the missing two bits and assume older implementations
> > comply with the spec and set bits [29:28] to 0.
>
> Ah, I don't think it ever even crossed my mind to look for changes here, but 
> of course if the node regions have grown from 16KB to 64KB then it's only 
> natural that offsets grow to match. I expect the CMN-700 config that we 
> tested on internally would have been small enough for this not to make a 
> difference. Thanks for the catch!
>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
>
> > Signed-off-by: Ilkka Koskinen <ilkka@xxxxxxxxxxxxxxxxxxxxxx>
> > ---
> >
> > I have tested this patch on CMN-600 and CMN-650.
> >
> > drivers/perf/arm-cmn.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> > index 80d8309652a4..b80a9b74662b 100644
> > --- a/drivers/perf/arm-cmn.c
> > +++ b/drivers/perf/arm-cmn.c
> > @@ -36,7 +36,7 @@
> >   #define CMN_CI_CHILD_COUNT		GENMASK_ULL(15, 0)
> >   #define CMN_CI_CHILD_PTR_OFFSET		GENMASK_ULL(31, 16)
> >   -#define CMN_CHILD_NODE_ADDR		GENMASK(27, 0)
> > +#define CMN_CHILD_NODE_ADDR		GENMASK(29, 0)
> >   #define CMN_CHILD_NODE_EXTERNAL		BIT(31)
> >     #define CMN_MAX_DIMENSION		12