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Sat, 03 Jan 2026 10:42:45 -0800 (PST) X-Google-Smtp-Source: AGHT+IGQVx5ArkItgm3P3dalXhu5nbT23BXFFl3dDv5MC+trY9KiLsHnUE94+iuUcA835+N77O3fCQ== X-Received: by 2002:a05:6a00:ad02:b0:7f7:3749:d97c with SMTP id d2e1a72fcca58-7ff657a37e5mr40323067b3a.22.1767465764958; Sat, 03 Jan 2026 10:42:44 -0800 (PST) Received: from [192.168.1.3] ([122.169.221.137]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7ff7a93b516sm43782587b3a.6.2026.01.03.10.42.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 03 Jan 2026 10:42:44 -0800 (PST) Message-ID: <07eeceaa-4f0e-4671-9ce9-8368c76e7d63@oss.qualcomm.com> Date: Sun, 4 Jan 2026 00:12:39 +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 Thunderbird Subject: Re: [PATCH 1/3] dt-bindings: interconnect: add clocks property to enable QoS on qcs8300 To: Krzysztof Kozlowski , Georgi Djakov , 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: <20251128150106.13849-1-odelu.kukatla@oss.qualcomm.com> <20251128150106.13849-2-odelu.kukatla@oss.qualcomm.com> <54ee48cf-9a00-4132-9ca6-bad65e08990a@kernel.org> Content-Language: en-US From: Odelu Kukatla In-Reply-To: <54ee48cf-9a00-4132-9ca6-bad65e08990a@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Authority-Analysis: v=2.4 cv=Sc76t/Ru c=1 sm=1 tr=0 ts=69596326 cx=c_pps a=rEQLjTOiSrHUhVqRoksmgQ==:117 a=5iuJI5XSOpgSZ6Ruo5Rmiw==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=E--YsjGbu3XWsEhLv2MA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=2VI0MkxyNR6bbpdq8BZq:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTAzMDE2OSBTYWx0ZWRfX0Y/1SkIcLkbX 4xxYcntWm/HVOAAWSlX2bwQvujtWzC1rxe+WVtxAIClx8MaQlY92qt6Y1FQuWtKC0TPcL7MXaQ8 6EC17TmVcA4GDJzdKZrcT+l4KH12Q/W7VbxHiWdk4EIlLhjCtJeDxIrENA6yGVZzdh1x7Prd3fu PugBbAZhONPB0vUVqLlS9tRjDZkyJO5bVr7Ou5nhtqAVizInvc/HA67Gn6NiAh1ZgHh7aRTm9ei z6i8uomiNHAIZVVv9/RwAm67mPqejqXMXR0S1pkHpSnUEZmlpT4Gv/ILkK4hTAMtDYpoYJFXYwS ZXvON2yIaBdnNpfALdedm1P4823uzwuFLynZe98AJTv+zabqY+ZSWPzjBLN0jxFeyIviIPiJ43L XdR7JLJCssI0IuuXyhw3bQ1uJrO6rLhRjw7qoT1Zqea56nD2wEUV5Jn4VGVbtT4ViTTLwxsjnFJ sV7pYgJEe+ipDfn/S4g== X-Proofpoint-GUID: PQ3rkKEypwE26zjOjW0lovZbG9Dhh5Gk X-Proofpoint-ORIG-GUID: PQ3rkKEypwE26zjOjW0lovZbG9Dhh5Gk X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-03_03,2025-12-31_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 spamscore=0 bulkscore=0 impostorscore=0 adultscore=0 phishscore=0 suspectscore=0 clxscore=1015 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2512120000 definitions=main-2601030169 On 12/23/2025 7:15 PM, Krzysztof Kozlowski wrote: > On 22/12/2025 18:38, Odelu Kukatla wrote: >> >> >> On 11/29/2025 3:03 PM, Krzysztof Kozlowski wrote: >>> On 28/11/2025 16:01, Odelu Kukatla wrote: >>>> Add 'clocks' property to enable QoS configuration. This property >>>> enables the necessary clocks for QoS configuration. >>>> >>>> QoS configuration is essential for ensuring that latency sensitive >>>> components such as CPUs and multimedia engines receive prioritized >>>> access to memory and interconnect resources. This helps to manage >>>> bandwidth and latency across subsystems, improving system responsiveness >>>> and performance in concurrent workloads. >>> >>> I don't see how clocks property help here at all. Are you getting clock >>> rates in the driver of some other clocks to make QoS decisions? >>> >> >> We don't need to get clock rate/frequency, just need to enable the >> clock(s) for QoS register access for which we need to get the clock >> handle in driver. > > Not relevant what your driver does. Still getting clock does not improve > system responsiveness. If you claim otherwise give me an argument or any > sort of proof that providing clock has impact on system responsiveness. > > IOW, don't feed us marketing. It's waste of our time. > > Hi Krzysztof, Thanks for the feedback. You are right that the clocks property itself does not improve system responsiveness. The QoS registers are inside a block whose interface is clock-gated, so the driver must enable the required clock before accessing those registers. The clocks property is only there to let the driver obtain that clock handle and enable the required clock; without that, the QoS registers are not accessible. The actual QoS behaviour is determined entirely by the values written to those registers, not by the presence of the clocks property in DT. About the “optional” wording: that was incorrect on my side. I will: 1.update the binding so that the `clocks` property accurately reflects the hardware and does not allow describing non-existing hardware, and 2.drop the “optional” wording and the performance oriented description from the commit message, keeping it to a minimal statement that the clock is needed to access the QoS registers. I’ll send a v2 with these changes. Best regards, Odelu > >> >>>> >>>> Both 'reg' and 'clocks' properties are optional. If either is missing, >>> >>> No! They are not. How they can be optional in the hardware? How SoC can >>> have for ONE GIVEN device optional reg, meaning one board with the same >>> Soc has the IO address space but other board with the same SoC does not >>> have it. >>> >> >> I agree, I will drop the “optional” wording and rework the schema so > > So why were they optional in the first place? What is this patch describing? > > > Best regards, > Krzysztof