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Thu, 05 Dec 2024 10:17:24 +0000 (GMT) Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA05.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 4B5AHNdU020454 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 5 Dec 2024 10:17:23 GMT Received: from [10.190.163.187] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Thu, 5 Dec 2024 02:17:17 -0800 Message-ID: <6356241e-6bfc-c4dc-1fbd-cd92f1b236ba@quicinc.com> Date: Thu, 5 Dec 2024 15:47:14 +0530 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH V4 4/5] soc: qcom: Introduce SCMI based Memlat (Memory Latency) governor Content-Language: en-US To: , Dmitry Baryshkov , Kyungmin Park , Chanwoo Choi , Viresh Kumar CC: "sudeep.holla@arm.com" , "cristian.marussi@arm.com" , "andersson@kernel.org" , "konrad.dybcio@linaro.org" , "robh+dt@kernel.org" , "krzysztof.kozlowski+dt@linaro.org" , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "quic_rgottimu@quicinc.com" , "quic_kshivnan@quicinc.com" , "conor+dt@kernel.org" , "arm-scmi@vger.kernel.org" , Amir Vajid References: <20241007061023.1978380-1-quic_sibis@quicinc.com> <20241007061023.1978380-5-quic_sibis@quicinc.com> <2aycrvnvivcrqctqmweadcgenwugafdr6ub3bzkscterpenz32@bzabln2hkral> <29eef87e-96f6-5105-6f7a-a8e01efcb4a3@quicinc.com> <20241115003809epcms1p518df149458f3023d33ec6d87a315e8f6@epcms1p5> From: Sibi Sankar In-Reply-To: <20241115003809epcms1p518df149458f3023d33ec6d87a315e8f6@epcms1p5> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: j-5sSJzGurTdnMTU9b402_166u-cHYBA X-Proofpoint-ORIG-GUID: j-5sSJzGurTdnMTU9b402_166u-cHYBA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 bulkscore=0 mlxscore=0 mlxlogscore=981 lowpriorityscore=0 clxscore=1015 malwarescore=0 priorityscore=1501 spamscore=0 adultscore=0 suspectscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2412050073 On 11/15/24 06:08, MyungJoo Ham wrote: >> >> Hey Dmitry, >> >> Thanks for taking time to review the series. >> >> + Devfreq maintainers to comment (I thought you already added >> them by name) >> >> >> Hey MyungJoo/Kyungmin/Chanwoo, >> >> Can you weigh in here? Does it make sense to add a new >> class of devfreq devices that don't have governors >> associated with them just for them to export a few >> essential data to userspace? In this scenario the >> scaling algorithm is in a SCP and we just start >> them from the kernel. We do have ways to get the >> current frequency of various buses but does this >> warrant adding a new class of governor less devices? >> >> -Sibi > > If voltage/frequency is controlled by SCP > (it's an SoC's internal hardware IP, right?), > it's good to have a userspace governer > with the driver not accepting updates from userspace. > > E.g., Let "target" callback not update the frequency value, > or let "target" callback always return an error with > a dev_err message that you don't accept frequency changes > from userspace. Thanks for the input. Will implement something similar to what you suggested for the next re-spin. -Sibi > > Cheers, > MyungJoo.