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[130.180.211.218]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-458705c4cacsm13878835e9.24.2025.07.24.03.04.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Jul 2025 03:04:28 -0700 (PDT) Message-ID: Date: Thu, 24 Jul 2025 12:04:27 +0200 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: [tip: timers/clocksource] clocksource/drivers/exynos_mct: Don't register as a sched_clock on arm64 To: Ingo Molnar , linux-kernel@vger.kernel.org, Thomas Gleixner Cc: linux-tip-commits@vger.kernel.org, Donghoon Yu , Youngmin Nam , John Stultz , Will McVicker , x86@kernel.org References: <20250620181719.1399856-3-willmcvicker@google.com> <175325504976.1420.2666973232153470630.tip-bot2@tip-bot2> Content-Language: en-US From: Daniel Lezcano In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 24/07/2025 07:16, Ingo Molnar wrote: > > * tip-bot2 for Will McVicker wrote: > >> The following commit has been merged into the timers/clocksource branch of tip: >> >> Commit-ID: 394b981382e6198363cf513f6eb6be4c55b22e44 >> Gitweb: https://git.kernel.org/tip/394b981382e6198363cf513f6eb6be4c55b22e44 >> Author: Will McVicker >> AuthorDate: Fri, 20 Jun 2025 11:17:05 -07:00 >> Committer: Daniel Lezcano >> CommitterDate: Tue, 15 Jul 2025 13:00:50 +02:00 >> >> clocksource/drivers/exynos_mct: Don't register as a sched_clock on arm64 >> >> The MCT register is unfortunately very slow to access, but importantly >> does not halt in the c2 idle state. So for ARM64, we can improve >> performance by not registering the MCT for sched_clock, allowing the >> system to use the faster ARM architected timer for sched_clock instead. >> >> The MCT is still registered as a clocksource, and a clockevent in order >> to be a wakeup source for the arch_timer to exit the "c2" idle state. >> >> Since ARM32 SoCs don't have an architected timer, the MCT must continue >> to be used for sched_clock. Detailed discussion on this topic can be >> found at [1]. >> >> [1] https://lore.kernel.org/linux-samsung-soc/1400188079-21832-1-git-send-email-chirantan@chromium.org/ >> >> [Original commit from https://android.googlesource.com/kernel/gs/+/630817f7080e92c5e0216095ff52f6eb8dd00727 >> >> Signed-off-by: Donghoon Yu >> Signed-off-by: Youngmin Nam >> Reviewed-by: Youngmin Nam >> Acked-by: John Stultz >> Tested-by: Youngmin Nam >> Signed-off-by: Will McVicker >> Link: https://lore.kernel.org/r/20250620181719.1399856-3-willmcvicker@google.com >> Signed-off-by: Daniel Lezcano > > The whole SOB chain of this commit is messy and has several serious > problems: > > 1) > > This commit has misattributed authorship: the first SOB is: > > Signed-off-by: Donghoon Yu > > but the Author field is not Donghoon Yu: > > Author: Will McVicker Yes, you are right. I should have pay more attention to author / sob, thanks for spotting it. > 2) > > The Reviewed-by tag is misapplied: > >> Signed-off-by: Youngmin Nam >> Reviewed-by: Youngmin Nam > > When someone passes along a patch, it's implicit that they have > reviewed it. Well my understanding of the SOB chain for these is the Signed-off-by from Youngmin is in the delivery path because it went first to the AOSP, then carried on to Linux by Will. Then Reviewed-by Youngmin letting us know the port from AOSP to Linux is ok. > 3) > > There's also a stray Tested-by tag by one of the SOB entries: > >> Signed-off-by: Youngmin Nam >> Reviewed-by: Youngmin Nam >> Tested-by: Youngmin Nam > > When someone passes along a patch, it's implicit that they not only > have reviewed the patch, but have also tested it to a certain extent In this specific case where the original commit is from AOSP, this chain seems to make sense. Souns like: "I was in the original commit delivery path" "I reviewed this patch carried to Linux" "I tested it on Linux" > ... > > 4) > > Why is the 'Link' tag just in the middle of the SOB chain, instead at the end of it? I don't know. Link must be at the end It is stated somewhere in the documentation? I use git b4 -s and the tool adds the Link then my sign off. > Presumably this is the proper SOB chain: > >> Author: Donghoon Yu > >> Signed-off-by: Donghoon Yu >> Signed-off-by: Youngmin Nam >> Signed-off-by: Will McVicker >> Signed-off-by: Daniel Lezcano >> Acked-by: John Stultz >> Link: https://lore.kernel.org/r/20250620181719.1399856-3-willmcvicker@google.com > > Correct? -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog