Re: [RFC PATCH] interconnect: qcom: icc-rpm: Don't call __qcom_icc_set twice on the same node

[Bryan O'Donoghue]

On 03/03/2023 11:39, Konrad Dybcio wrote:
> On 3.03.2023 12:36, Bryan O'Donoghue wrote:
> > On 03/03/2023 11:35, Bryan O'Donoghue wrote:
> > > On 03/03/2023 11:33, Konrad Dybcio wrote:
> > > > On 3.03.2023 12:32, Bryan O'Donoghue wrote:
> > > > > On 03/03/2023 02:35, Konrad Dybcio wrote:
> > > > > > Currently, when sync_state calls set(n, n) all the paths for setting
> > > > > > parameters on an icc node are called twice. Avoid that.
> > > > > >
> > > > > > Fixes: 751f4d14cdb4 ("interconnect: icc-rpm: Set destination bandwidth as well as source bandwidth")
> > > > > > Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
> > > > > > ---
> > > > > > RFC comes from the fact that I *believe* this should be correct, but I'm
> > > > > > not entirely sure about it..
> > > > > >
> > > > > >
> > > > > >     drivers/interconnect/qcom/icc-rpm.c | 2 +-
> > > > > >     1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> > > > > > index a6e0de03f46b..d35db1af9b08 100644
> > > > > > --- a/drivers/interconnect/qcom/icc-rpm.c
> > > > > > +++ b/drivers/interconnect/qcom/icc-rpm.c
> > > > > > @@ -387,7 +387,7 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst)
> > > > > >         ret = __qcom_icc_set(src, src_qn, sum_bw);
> > > > > >         if (ret)
> > > > > >             return ret;
> > > > > > -    if (dst_qn) {
> > > > > > +    if (dst_qn && src_qn != dst_qn) {
> > > > > >             ret = __qcom_icc_set(dst, dst_qn, sum_bw);
> > > > > >             if (ret)
> > > > > >                 return ret;
> > > > >
> > > > > Is it possible for src_qn == dst_qn ?
> > > > As the commit message says, sync_state calls set(n, n) in
> > > > drivers/interconnect/core.c : icc_sync_state(struct device *dev)
> > >
> > > So you've _seen_ that happen ?
> >
> > Assuming you have, then why isn't the fix in sync_state i.e. that's an error for everybody right ?
> I believe that there's simply no other way of updating every single node
> on its own with the icc api, without taking any links into play. But I
> see exynos and i.mx also effectively calling it twice on each node.
>
> Konrad

I mean. I'm fine for you to retain my RB on this qcom specific patch 
since this seems like a real bug to me but... it seems like a generic 
bug across arches that should probably be resolved @ the higher level.

?

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bod