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[130.180.211.218]) by smtp.googlemail.com with ESMTPSA id f24-20020a05600c491800b003d9e74dd9b2sm2938429wmp.9.2023.01.18.14.14.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Jan 2023 14:14:23 -0800 (PST) Message-ID: Date: Wed, 18 Jan 2023 23:14:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH v5 0/3] Thermal ACPI APIs for generic trip points Content-Language: en-US To: srinivas pandruvada , "Zhang, Rui" , "rafael@kernel.org" Cc: "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "christophe.jaillet@wanadoo.fr" , "linux-acpi@vger.kernel.org" References: <20230113180235.1604526-1-daniel.lezcano@linaro.org> <2627c37e07dce6b125d3fea3bf38a5f2407ad6a1.camel@intel.com> <5aabdd3010a02e361fbbe01f4af0e30d11f0ae6b.camel@linux.intel.com> <8547963350fb3bdb09a4693f0eb80c7199ab6f21.camel@linux.intel.com> <87627e1f-322c-a195-8ce6-8922d9787ff0@linaro.org> <340f3ecdaddb2c422dcbe3df712a082f333eab0d.camel@linux.intel.com> From: Daniel Lezcano In-Reply-To: <340f3ecdaddb2c422dcbe3df712a082f333eab0d.camel@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/01/2023 22:16, srinivas pandruvada wrote: > On Wed, 2023-01-18 at 22:01 +0100, Daniel Lezcano wrote: >> On 18/01/2023 21:53, srinivas pandruvada wrote: >>> On Wed, 2023-01-18 at 21:00 +0100, Daniel Lezcano wrote: >>>> On 18/01/2023 20:16, srinivas pandruvada wrote: >>>> >>>> [ ... ] >>>> >>>>>>> But we'd better wait for the thermald test result from >>>>>>> Srinvias. >>>>>> >>>>>> A quick test show that things still work with thermald and >>>>>> these >>>>>> changes. >>>>> >>>>> But I have a question. In some devices trip point temperature >>>>> is >>>>> not >>>>> static. When hardware changes, we get notification. For example >>>>> INT3403_PERF_TRIP_POINT_CHANGED for INT3403 drivers. >>>>> Currently get_trip can get the latest changed value. But if we >>>>> preregister, we need some mechanism to update them. >>>> >>>> When the notification INT3403_PERF_TRIP_POINT_CHANGED happens, we >>>> call >>>> int340x_thermal_read_trips() which in turn updates the trip >>>> points. >>>> >>> >>> Not sure how we handle concurrency here when driver can freely >>> update >>> trips while thermal core is using trips. >> >> Don't we have the same race without this patch ? The thermal core can >> call get_trip_temp() while there is an update, no ? > Yes it is. But I can add a mutex locally here to solve. > But not any longer. > > I think you need some thermal_zone_read_lock/unlock() in core, which > can use rcu. Even mutex is fine as there will be no contention as > updates to trips will be rare. I was planning to provide a thermal_trips_update(tz, trips) and from there handle the locking. As the race was already existing, can we postpone this change after the generic trip points changes? There is still a lot of work to do to consolidate the code. One of them is to provide a generic function to browse the trip points and ensure the code is using it instead of directly inspect the thermal zone internals structure. I'm almost there but I need the remaining Intel drivers changes to be merged (as well as ACPI which is finished but depending on this series). -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog