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[81.204.249.205]) by smtp.gmail.com with ESMTPSA id p12-20020a7bcc8c000000b003a682354f63sm5063992wma.11.2022.10.30.12.45.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 30 Oct 2022 12:45:13 -0700 (PDT) Message-ID: <1e268275-0705-8c30-5ea8-799d17278f08@gmail.com> Date: Sun, 30 Oct 2022 20:45:12 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH v1 1/2] arm: rockchip: Kconfig: remove select ARM_GLOBAL_TIMER To: Heiko Stuebner Cc: linux@armlinux.org.uk, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org References: <88e93a81-ef9f-adcc-db83-f8b5ba615c47@gmail.com> <3935573.e9J7NaK4W3@phil> Content-Language: en-US From: Johan Jonker In-Reply-To: <3935573.e9J7NaK4W3@phil> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/30/22 20:30, Heiko Stuebner wrote: > Hi Johan, > > Am Sonntag, 30. Oktober 2022, 19:36:01 CET schrieb Johan Jonker: >> The clocksource and the sched_clock provided by the arm_global_timer >> on Rockchip rk3066a/rk3188 are quite unstable because their rates >> depend on the cpu frequency. >> >> Recent changes to the arm_global_timer driver makes it impossible to use. >> >> On the other side, the arm_global_timer has a higher rating than the >> rockchip_timer, it will be selected by default by the time framework >> while we want to use the stable rockchip clocksource. >> >> Let's disable the arm_global_timer in order to have the ROCKCHIP_TIMER >> (rk3188) or DW_APB_TIMER (rk3066a) selected by default. > > Doing that change won't help you with the issue you see. > These days kernel images are supposed to run on as many > platforms as possible with the _same_ kernel image. > > So the muliplatform image build from the kernel's defconfig will > include most of the time other platforms that will pull in the > global-timer again. > > How about "imply" instead of "select"? It's no longer useful. One can get rid of if one wants a really lean kernel. > I do see that you disable the global-timer > in the rk3066 dtsi in patch2, though this would leave the rk3188 > still using the global-timer. Why not do this in the rk3xxx.dtsi? > > I.e. keep the global-timer node, but add a disabled property > together with a comment above the status=disabled, describing > the issue. [This should keep people from re-adding the global-timer > in the future :-) ] > > Thanks > Heiko > >> Signed-off-by: Johan Jonker >> --- >> >> ARM: dts: rockchip: disable arm-global-timer for rk3188 >> https://lore.kernel.org/linux-rockchip/1492374441-23336-26-git-send-email-daniel.lezcano@linaro.org/ >> >> clocksource: arm_global_timer: implement rate compensation whenever source clock changes >> https://lore.kernel.org/all/20210406130045.15491-2-andrea.merello@gmail.com/ >> --- >> arch/arm/mach-rockchip/Kconfig | 2 -- >> 1 file changed, 2 deletions(-) >> >> diff --git a/arch/arm/mach-rockchip/Kconfig b/arch/arm/mach-rockchip/Kconfig >> index b7855cc66..0432a4430 100644 >> --- a/arch/arm/mach-rockchip/Kconfig >> +++ b/arch/arm/mach-rockchip/Kconfig >> @@ -15,8 +15,6 @@ config ARCH_ROCKCHIP >> select DW_APB_TIMER_OF >> select REGULATOR if PM >> select ROCKCHIP_TIMER >> - select ARM_GLOBAL_TIMER >> - select CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK >> select ZONE_DMA if ARM_LPAE >> select PM >> help >> -- >> 2.20.1 >> >> > > > >