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Wed, 03 Sep 2025 11:01:38 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFeb9eLZArrjeEJcIg/7Rx3a/Fa169OALXNV2q0nNF+8FgBvv+z9E0vUippWGNtAeLloBrrCg== X-Received: by 2002:a17:90b:1b12:b0:327:7c8e:8720 with SMTP id 98e67ed59e1d1-328156e57demr19444658a91.34.1756922497588; Wed, 03 Sep 2025 11:01:37 -0700 (PDT) Received: from [192.168.1.8] ([136.185.244.63]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-327da90e423sm18122214a91.20.2025.09.03.11.01.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Sep 2025 11:01:37 -0700 (PDT) Message-ID: <6cdeac85-a803-4b75-8fb5-c9d485ae374c@oss.qualcomm.com> Date: Wed, 3 Sep 2025 23:31:30 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] dt-bindings: interconnect: add clocks property to enable QoS on sa8775p To: Konrad Dybcio , Georgi Djakov , Krzysztof Kozlowski , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio Cc: Raviteja Laggyshetty , Dmitry Baryshkov , Bartosz Golaszewski , linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Tipton References: <20250808140300.14784-1-odelu.kukatla@oss.qualcomm.com> <20250808140300.14784-2-odelu.kukatla@oss.qualcomm.com> <90b51e31-3217-4483-bb5b-ec328665a723@kernel.org> <28b97952-1b67-411f-a7fb-ddd558739839@oss.qualcomm.com> <7d3e5cf7-4167-4005-ba4b-c1915c254705@oss.qualcomm.com> <00f50d92-e4ea-4805-b771-147fa5f5ebe4@kernel.org> <249f8109-31b1-4cb8-a5a4-b30c27b2e987@oss.qualcomm.com> <6e036d6a-f2d1-43d6-bb35-54467edd7ec9@kernel.org> <26e5309e-3705-4d70-a2e7-3f0e9344816b@kernel.org> <3c4751c3-52d5-408e-ae80-df22bcff5d8a@oss.qualcomm.com> Content-Language: en-US From: Odelu Kukatla In-Reply-To: <3c4751c3-52d5-408e-ae80-df22bcff5d8a@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: 9y7lucm0Eu0_FsL1_WytFHHRi9qat6Wr X-Proofpoint-GUID: 9y7lucm0Eu0_FsL1_WytFHHRi9qat6Wr X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODMwMDAyMCBTYWx0ZWRfX/ghDdqEFQoqI MMrnlI6dteLuLzwu64aksmelh6nUwe5x8z8ctDkOZhtk3j/+Lwi90uvEEvtNahqosmd4DkHFsoR 5XFlc90zz7SwWJB8bRQEY3g+UxfWHH93/MB053V1qwYZ+RLe2CLi3gI9edYA/9Xv+XDTwVaYzvR xWV7/WyybmVBHJZi1IgEuYZlojjwRVuOHiWvhK3KcrYDZOtw3URpN3q6tEuA2ws+yDiNR3nOw23 yA56lcYuV080KXBqaDoXWuswwSeGITApjlU9GfdtjQuGyzN9GopdEYnBRMdkZMA4GrBTg0Twnqa vLtSCfXsqp+dnyo2sU1L9F3P7EI0b9G09Jhx2BnBZdv6AzJcFcgB3LD1kQ2RuyTJ0fxyNVXguMP l0XeUpsH X-Authority-Analysis: v=2.4 cv=VNndn8PX c=1 sm=1 tr=0 ts=68b88283 cx=c_pps a=Qgeoaf8Lrialg5Z894R3/Q==:117 a=yA1qRYK8n1cH6pNkam3zVg==:17 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=8_klXzSyxtcaGXXTCUoA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=x9snwWr2DeNwDh03kgHS:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-03_09,2025-08-28_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 impostorscore=0 malwarescore=0 bulkscore=0 clxscore=1015 adultscore=0 priorityscore=1501 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508300020 On 9/3/2025 6:12 PM, Konrad Dybcio wrote: > On 8/28/25 11:59 PM, Georgi Djakov wrote: >> On 8/28/25 9:20 PM, Krzysztof Kozlowski wrote: >>> On 28/08/2025 20:16, Odelu Kukatla wrote: >>>> >>>>>> QoS configuration is essential for managing latency and bandwidth across >>>>>> subsystems such as CPU, GPU, and multimedia engines. Without it, the >>>>>> system may experience performance degradation, especially under >>>>> >>>>> So how was it working for the last 2 years? >>>>> >>>> The system may function normally without this feature. However, enabling >>> >>> >>> Huh? So you agree but keep continuing the discussion? >>> >>> I don't understand what we are discussing in such case, but just to >>> close the topic from my side and be explicit: based on above you cannot >>> break the ABI. >> >> To be even more specific, if we already have some DT binding without any >> clocks and reg properties, we can't just suddenly change them from now >> on to be "required". But they can still be "optional" and this will not >> break the ABI, right? The old DT is still valid and the QoS will be >> active when the new properties are present and this is handled properly >> by the driver. > > Correct and this very approach was used to retrofit QoS onto an even older > sc7280 icc driver. > > The icc-rpmh core already ignores QoS configuration if the clocks are not > provided. > > Konrad Thanks Krzysztof, Georgi, Konrad for the detailed discussion. To summarize: we can’t make reg and clocks properties required now for sa8775p, and making these properties optional ensures backward compatibility. I will address this in the next revision. Thanks again for the comments. Best regards, Odelu