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Wysocki" Subject: Re: [RFC 0/3] Introduce cpufreq minimum load QoS Thread-Topic: [RFC 0/3] Introduce cpufreq minimum load QoS Thread-Index: AQHWGi06wBgeAQBseECYOK/U7Qvw76iQJdAAgAACCYA= Date: Wed, 29 Apr 2020 15:57:21 +0000 Message-ID: <30cdecf9-703a-eb2b-7c2b-f1e21c805add@st.com> References: <20200424114058.21199-1-benjamin.gaignard@st.com> <7657495.QyJl4BcWH5@kreacher> In-Reply-To: <7657495.QyJl4BcWH5@kreacher> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.75.127.51] Content-ID: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-29_08:2020-04-29, 2020-04-29 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200429_085738_771355_C5996638 X-CRM114-Status: GOOD ( 16.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "mcoquelin.stm32@gmail.com" , Alexandre TORGUE , "len.brown@intel.com" , "viresh.kumar@linaro.org" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Patrick Bellasi , "pavel@ucw.cz" , Hugues FRUCHET , "mchehab@kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 4/29/20 5:50 PM, Rafael J. Wysocki wrote: > On Friday, April 24, 2020 1:40:55 PM CEST Benjamin Gaignard wrote: >> When start streaming from the sensor the CPU load could remain very low >> because almost all the capture pipeline is done in hardware (i.e. without >> using the CPU) and let believe to cpufreq governor that it could use lower >> frequencies. If the governor decides to use a too low frequency that >> becomes a problem when we need to acknowledge the interrupt during the >> blanking time. >> The delay to ack the interrupt and perform all the other actions before >> the next frame is very short and doesn't allow to the cpufreq governor to >> provide the required burst of power. That led to drop the half of the frames. >> >> To avoid this problem, DCMI driver informs the cpufreq governors by adding >> a cpufreq minimum load QoS resquest. > This seems to be addressing a use case that can be addressed with the help of > utilization clamps with less power overhead. Do mean clamping the policy frequencies ? I may have miss the API to do that... > > Thanks! > > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel