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[130.180.211.218]) by smtp.googlemail.com with ESMTPSA id 4fb4d7f45d1cf-5cbb625526csm3441005a12.6.2024.10.28.07.54.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Oct 2024 07:54:49 -0700 (PDT) Message-ID: <3c98775b-b61b-478f-838e-59f8e1cf8aed@linaro.org> Date: Mon, 28 Oct 2024 15:54:48 +0100 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: [PATCH v7 05/12] clocksource: mips-gic-timer: Always use cluster 0 counter as clocksource To: Aleksandar Rikalo , Thomas Bogendoerfer Cc: Chao-ying Fu , Geert Uytterhoeven , Greg Ungerer , Hauke Mehrtens , Ilya Lipnitskiy , Jiaxun Yang , linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, Marc Zyngier , Paul Burton , Peter Zijlstra , Serge Semin , Thomas Gleixner , Tiezhu Yang , Gregory CLEMENT References: <20241019071037.145314-1-arikalo@gmail.com> <20241019071037.145314-6-arikalo@gmail.com> Content-Language: en-US From: Daniel Lezcano In-Reply-To: <20241019071037.145314-6-arikalo@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 19/10/2024 09:10, Aleksandar Rikalo wrote: > From: Paul Burton > > In a multi-cluster MIPS system, there are multiple GICs - one in each > cluster - each of which has its independent counter. The counters in > each GIC are not synchronized in any way, so they can drift relative > to one another through the lifetime of the system. This is problematic > for a clock source which ought to be global. > > Avoid problems by always accessing cluster 0's counter, using > cross-cluster register access. This adds overhead so it is applied only > on multi-cluster systems. > > Signed-off-by: Paul Burton > Signed-off-by: Chao-ying Fu > Signed-off-by: Dragan Mladjenovic > Signed-off-by: Aleksandar Rikalo > Tested-by: Serge Semin > --- May I take this patch through the clocksource tree ? -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog