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Wed, 19 Aug 2026 06:01:02 -0700 (PDT) X-Received: by 2002:a05:620a:1728:b0:936:2f59:dfe4 with SMTP id af79cd13be357-9371e1af3d1mr306215585a.0.1787144461995; Wed, 19 Aug 2026 06:01:01 -0700 (PDT) Received: from [192.168.120.193] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5b478854951sm502596e87.3.2026.08.19.06.00.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Aug 2026 06:01:00 -0700 (PDT) Message-ID: Date: Wed, 19 Aug 2026 15:00:57 +0200 Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] clk: qcom: ipq-cmn-pll: keep the CMN block bus clocks enabled To: Jie Luo , Stanislaw Pal Cc: Bjorn Andersson , Stephen Boyd , Michael Turquette , Mieczyslaw Nalewaj , Brian Masney , linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260730191353.557494-1-kuncy7@gmail.com> <20260803091003.15285-1-kuncy7@gmail.com> <8af46926-fecc-4396-973e-2290ae285998@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <8af46926-fecc-4396-973e-2290ae285998@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Authority-Analysis: v=2.4 cv=QedWeMbv c=1 sm=1 tr=0 ts=6a85a90f cx=c_pps a=qKBjSQ1v91RyAK45QCPf5w==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=Cml0np4gJbHuCS8qjCYA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=NFOGd7dJGGMPyQGDc5-O:22 X-Proofpoint-ORIG-GUID: mih8dI2yM5s0WGwKTfZXn6NvgZ4bCtSo X-Proofpoint-Spam-Info: AW1haW4tMjYwODE5MDEwMCBTYWx0ZWRfX009y1bAx10W+ eFPdTDghXONHiqXwoxMoUXdzLMo76R/x4OR5XMHYJanMIijfMI4u4GufCS5KaNp+sozX3Y2nFHL xLRzNCCdN0w1JPLDlL54UdHnT/z/vhk= X-Proofpoint-GUID: mih8dI2yM5s0WGwKTfZXn6NvgZ4bCtSo X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE5MDEwMCBTYWx0ZWRfX6kyP2gkC647X m9Jli2I0q4Vnpto6l3l78fPSEghitFDYW1UoSxyTo2EXlA+OQ7ux/QDyM+GwPPdNYhxKq40JUlH E0LUSpjpo2AzO/BsNjXN7bnZWU02JugxrkIbq2fYVUtqytJ3oQ3e5eqcJlBQlCEA83VUKxApZ1v 0j+EoKGrKv7PsTkPG31tkWn9FId6nBco2NF1RdYO2wwWIsuOIPEI5AxRinabbNTdrsxv7gnGkXH qQqd6yEN54iZgMuC44j6znECvSq+hcbf5dw4q3nWhuLwK44xi3i4wgDZxkr19l1t818c9VUaM5c EP8WLF7X+s4WkSXAjzEEUbwOTf8GBM9qC3LBuYFZBl2yKkDcbNjb19YY/Jyp0zgBMadaHXOK/P3 t29Tcg4YgSD9PsLhRcBFyLeRo2m2+FIAi4lveJ06G6UJbZ0z8PjpmI7QZnCVryJRWTNzgFCcbND 6NkugoSalHrUklQJUpw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-19_03,2026-08-19_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 adultscore=0 malwarescore=0 impostorscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608190100 On 8/4/26 1:03 PM, Jie Luo wrote: > > > On 8/3/2026 5:10 PM, Stanislaw Pal wrote: >>> The CMN PLL AHB/SYS clocks will remain enabled as long as a downstream >>> consumer of the CMN PLL clocks is active — this behaviour was confirmed >>> experimentally on the IPQ9574 platform as example. >> That is exactly the mechanism - and it is exactly what IPQ5018 does not >> have. On IPQ9574 the nsscc node consumes the CMN PLL outputs in DT: >> >> ipq9574.dtsi: >> nsscc: clock-controller@39b00000 { >> clocks = <&xo_board_clk>, >> <&cmn_pll NSS_1200MHZ_CLK>, >> <&cmn_pll PPE_353MHZ_CLK>, ... >> >> so the device link holds the supplier active, which is what your >> insmod/devmem experiment shows. >> >> On IPQ5018 there is no such consumer: nothing in ipq5018.dtsi references >> any cmn_pll output clock - the only occurrences of the phandle are the >> provider node itself and its own assigned-clocks. The actual users of >> the CMN outputs on this SoC (the internal GE PHY and the uniphy blocks) >> take them directly in hardware, with no DT linkage, so no device link >> ever holds the provider active. A few ms after probe the autosuspend >> gates the AHB/SYS clocks, and the box dies on the next bus access - >> which is the measured behaviour the patch description quotes. > > The CMN PLL output clocks do not depend on the AHB or SYS clocks. They > continue to operate correctly at the fixed rates even when the AHB > and SYS clocks are disabled. Therefore, once the CMN PLL module is > loaded, its output clocks are expected to operate at the correct > frequencies. Linux sees there's no consumers for the clocks the CMN PLL provides and gates them, subsequently also gating the PLL itself as all of its children become offline. I can't find the docs that would show me what IPs consume this block, could you please help out here Jie? Konrad