Message-ID: <45156f6a-6f18-6d7c-5d4a-e66ea9cca724@linaro.org>
Date:   Thu, 23 Feb 2023 15:17:41 +0100
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Subject: Re: [PATCH v5 08/10] interconnect: qcom: msm8996: Specify no bus
 clock scaling on A0NoC
Content-Language: en-US
To:     Bjorn Andersson <andersson@kernel.org>
Cc:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Georgi Djakov <djakov@kernel.org>,
        Evan Green <evgreen@chromium.org>,
        Jun Nie <jun.nie@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Brian Masney <masneyb@onstation.org>,
        Yassine Oudjana <y.oudjana@protonmail.com>,
        Georgi Djakov <georgi.djakov@linaro.org>,
        Bryan O'Donoghue <bryan.odonoghue@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230217-topic-icc-fixes-v5-v5-0-c9a550f9fdb9@linaro.org>
 <20230217-topic-icc-fixes-v5-v5-8-c9a550f9fdb9@linaro.org>
 <8c4f1cc8-c1f8-06b6-53fe-7507d74ca958@linaro.org>
 <3c205131-632a-6592-5dc0-82313b26e5f6@linaro.org>
 <CAA8EJprJYPAsFZgu-DwjOHm6FsUEJ309zDo=Muh04L4B4oWhmw@mail.gmail.com>
 <5a2f502a-6530-dc8c-a81e-3d2a33964366@linaro.org>
 <20230223140710.72qcxcvyme5npf2v@ripper>
From:   Konrad Dybcio <konrad.dybcio@linaro.org>
In-Reply-To: <20230223140710.72qcxcvyme5npf2v@ripper>
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On 23.02.2023 15:07, Bjorn Andersson wrote:
> On Fri, Feb 17, 2023 at 09:28:54PM +0100, Konrad Dybcio wrote:
>>
>>
>> On 17.02.2023 21:26, Dmitry Baryshkov wrote:
>>> On Fri, 17 Feb 2023 at 21:53, Konrad Dybcio <konrad.dybcio@linaro.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@linaro.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?
>> I tested that locally before reporting the mistake on my side and
>> while it works, I just consider it.. ugly, because:
>>
>> num_clocks =
>>> 0 => use the externally specified num_/clocks (logical)
>> =0 => use the default 2
> 
> Why not let go of this "convenience" and have num_clocks actually mean
> number of clocks?
Sounds good.. Should I keep the default "bus", "bus_a" on absence of
.bus_clocks still, to avoid duplicating objects?

Konrad

> 
> Regards,
> Bjorn
> 
>> <0 => consider there's zero
>>
>> ..but maybe that's just me.. if you don't find it ugly, I may just
>> go with that.
>>
>> Konrad
>>>
>>>>
>>>> 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,
>>>>>>
>>>
>>>
>>>