Message-ID: <08020872-6316-8f81-ac6a-c6eef408818f@linaro.org>
Date:   Fri, 3 Mar 2023 11:36:35 +0000
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Subject: Re: [RFC PATCH] interconnect: qcom: icc-rpm: Don't call
 __qcom_icc_set twice on the same node
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From:   Bryan O'Donoghue <bryan.odonoghue@linaro.org>
To:     Konrad Dybcio <konrad.dybcio@linaro.org>,
        linux-arm-msm@vger.kernel.org, andersson@kernel.org,
        agross@kernel.org
Cc:     marijn.suijten@somainline.org, Georgi Djakov <djakov@kernel.org>,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230303023500.2173137-1-konrad.dybcio@linaro.org>
 <59b28fb4-1367-9872-ed63-90847e380bb6@linaro.org>
 <29513b9e-8561-7f7e-370e-7515116c7ee6@linaro.org>
 <3116a08a-30a8-c9b9-f079-26739c9e6d49@linaro.org>
In-Reply-To: <3116a08a-30a8-c9b9-f079-26739c9e6d49@linaro.org>
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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@linaro.org>
>>>> ---
>>>> 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 ?