linux-kernel - Re: [PATCH v5 08/10] interconnect: qcom: msm8996: Specify no bus clock scaling on A0NoC

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Message-ID: <CAA8EJprJYPAsFZgu-DwjOHm6FsUEJ309zDo=Muh04L4B4oWhmw@mail.gmail.com>
Date:   Fri, 17 Feb 2023 22:26:23 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Georgi Djakov <djakov@...nel.org>,
        Evan Green <evgreen@...omium.org>,
        Jun Nie <jun.nie@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Brian Masney <masneyb@...tation.org>,
        Yassine Oudjana <y.oudjana@...tonmail.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        "Bryan O'Donoghue" <bryan.odonoghue@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 08/10] interconnect: qcom: msm8996: Specify no bus
 clock scaling on A0NoC

On Fri, 17 Feb 2023 at 21:53, Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>
>
>
> On 17.02.2023 20:27, Konrad Dybcio wrote:
> >
> >
> > On 17.02.2023 11:46, Konrad Dybcio wrote:
> >> A0NoC only does bus scaling through RPM votes and does not have any
> >> ICC clocks. Describe this.
> >>
> >> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> >> ---
> > This is bad, as devm_clk_get_bulk{"", _optional} doesn't
> > check if num_clocks makes sense and passes "-1" down the
> > devres alloc chain..
> >
> > I'll rework this for the next revision by simply assigning
> > the common "bus", "bus_a" set everywhere instead of relying
> > on it being there by default..
> Or maybe I shouldn't, as that will require redefining the array
> over and over again.. Perhaps just passing <&xo_board>, <&xo_board>
> to a0noc's "bus", "bus_a", similar to what's been done on SDM630's
> GNoC would be less messy?

What about simply skipping a call to devm_clk_get if num_bus_clocks is negative?

>
> Konrad
> >
> > Konrad
> >>  drivers/interconnect/qcom/msm8996.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/interconnect/qcom/msm8996.c b/drivers/interconnect/qcom/msm8996.c
> >> index 1a5e0ad36cc4..45eb8675fb11 100644
> >> --- a/drivers/interconnect/qcom/msm8996.c
> >> +++ b/drivers/interconnect/qcom/msm8996.c
> >> @@ -1817,6 +1817,7 @@ static const struct qcom_icc_desc msm8996_a0noc = {
> >>      .type = QCOM_ICC_NOC,
> >>      .nodes = a0noc_nodes,
> >>      .num_nodes = ARRAY_SIZE(a0noc_nodes),
> >> +    .num_bus_clocks = -1, /* No bus clock scaling */
> >>      .intf_clocks = a0noc_intf_clocks,
> >>      .num_intf_clocks = ARRAY_SIZE(a0noc_intf_clocks),
> >>      .has_bus_pd = true,
> >>



-- 
With best wishes
Dmitry