From: Baolin Wang <baolin.wang@linaro.org> To: Chunyan Zhang <zhang.lyra@gmail.com> Cc: "Catalin Marinas" <catalin.marinas@arm.com>, "Will Deacon" <will.deacon@arm.com>, "Arnd Bergmann" <arnd@arndb.de>, "Linux ARM" <linux-arm-kernel@lists.infradead.org>, "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>, "Mark Brown" <broonie@kernel.org>, "Orson Zhai (翟京)" <orson.zhai@spreadtrum.com>, nianfu.bai@spreadtrum.com, "Geng Ren" <geng.ren@spreadtrum.com> Subject: Re: [PATCH] arm64: Enable SPRD_TIMER Date: Wed, 14 Feb 2018 11:49:09 +0800 [thread overview] Message-ID: <CAMz4kuK4gofFoWm8=UE72spqz5OUtkj82=aDC7c=0RwhuXi_Eg@mail.gmail.com> (raw) In-Reply-To: <CAAfSe-v_i=EnrvKWKmWsi4wSx=EiHK_0Q7KfouaQ8o5iYo+yrA@mail.gmail.com> Hi Chunyan, On 11 February 2018 at 19:41, Chunyan Zhang <zhang.lyra@gmail.com> wrote: > Hi Baolin, > > On 7 February 2018 at 11:12, Baolin Wang <baolin.wang@linaro.org> wrote: >> On 7 February 2018 at 10:31, Chunyan Zhang <zhang.lyra@gmail.com> wrote: >>> Hi Baolin, >>> >>> On 6 February 2018 at 18:36, Baolin Wang <baolin.wang@linaro.org> wrote: >>>> Enable Spreadtrum timer driver for Spreadtrum plaform, which will be used >>>> as tick broadcast device. >>>> >>>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> >>>> --- >>>> arch/arm64/Kconfig.platforms | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms >>>> index fbedbd8..3e0bbb0 100644 >>>> --- a/arch/arm64/Kconfig.platforms >>>> +++ b/arch/arm64/Kconfig.platforms >>>> @@ -224,6 +224,7 @@ config ARCH_TEGRA >>>> >>>> config ARCH_SPRD >>>> bool "Spreadtrum SoC platform" >>>> + select SPRD_TIMER >>> >>> Do we have to select SPRD_TIMER here? SC9836, SC9860 have been working >>> with a minimum system without SPRD TIMER. >> >> Yes, we need register this timer as the tick broadcast device, >> otherwise we will use one hrtimer to be registered the broadcast >> device, which will affect the No-Hz of CPU attaching the >> broadcast-hrtimer. > > Again, Spreadtrum's two boards - SC9836/SC9860 - can run into console > without SPRD_TIMER, we can also debug some kernel origianl feature or > some basic drivers on these two boards, such as CoreSight, clock > driver, etc. Ii think you misunderstood my meaning, I did not say it can not work without the SPRD TIMER. Let me try to explain it again, it we did not select the Spreadtrum timer, we will use one hrtimer to be the tick broadcast device, so in this situation, the cpu attaching the broadcast-hrtimer can not be entered into No-Hz to save power to avoid dead-lock issue. But if we register one timer as the tick broadcast device, then all cpus can be entered No-Hz to save power. So that's why we need select the SPRD_TIMER. > > In my opinion we should keep the kernel as simple as possible, the > above information can go to the 'help' graph of SPRD_TIMER in its > Kconfig. That's one optimization, not the issue of making the kernel more complicated. OK, I will add some kerneldoc to explain that. -- Baolin.wang Best Regards
WARNING: multiple messages have this Message-ID (diff)
From: baolin.wang@linaro.org (Baolin Wang) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: Enable SPRD_TIMER Date: Wed, 14 Feb 2018 11:49:09 +0800 [thread overview] Message-ID: <CAMz4kuK4gofFoWm8=UE72spqz5OUtkj82=aDC7c=0RwhuXi_Eg@mail.gmail.com> (raw) In-Reply-To: <CAAfSe-v_i=EnrvKWKmWsi4wSx=EiHK_0Q7KfouaQ8o5iYo+yrA@mail.gmail.com> Hi Chunyan, On 11 February 2018 at 19:41, Chunyan Zhang <zhang.lyra@gmail.com> wrote: > Hi Baolin, > > On 7 February 2018 at 11:12, Baolin Wang <baolin.wang@linaro.org> wrote: >> On 7 February 2018 at 10:31, Chunyan Zhang <zhang.lyra@gmail.com> wrote: >>> Hi Baolin, >>> >>> On 6 February 2018 at 18:36, Baolin Wang <baolin.wang@linaro.org> wrote: >>>> Enable Spreadtrum timer driver for Spreadtrum plaform, which will be used >>>> as tick broadcast device. >>>> >>>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> >>>> --- >>>> arch/arm64/Kconfig.platforms | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms >>>> index fbedbd8..3e0bbb0 100644 >>>> --- a/arch/arm64/Kconfig.platforms >>>> +++ b/arch/arm64/Kconfig.platforms >>>> @@ -224,6 +224,7 @@ config ARCH_TEGRA >>>> >>>> config ARCH_SPRD >>>> bool "Spreadtrum SoC platform" >>>> + select SPRD_TIMER >>> >>> Do we have to select SPRD_TIMER here? SC9836, SC9860 have been working >>> with a minimum system without SPRD TIMER. >> >> Yes, we need register this timer as the tick broadcast device, >> otherwise we will use one hrtimer to be registered the broadcast >> device, which will affect the No-Hz of CPU attaching the >> broadcast-hrtimer. > > Again, Spreadtrum's two boards - SC9836/SC9860 - can run into console > without SPRD_TIMER, we can also debug some kernel origianl feature or > some basic drivers on these two boards, such as CoreSight, clock > driver, etc. Ii think you misunderstood my meaning, I did not say it can not work without the SPRD TIMER. Let me try to explain it again, it we did not select the Spreadtrum timer, we will use one hrtimer to be the tick broadcast device, so in this situation, the cpu attaching the broadcast-hrtimer can not be entered into No-Hz to save power to avoid dead-lock issue. But if we register one timer as the tick broadcast device, then all cpus can be entered No-Hz to save power. So that's why we need select the SPRD_TIMER. > > In my opinion we should keep the kernel as simple as possible, the > above information can go to the 'help' graph of SPRD_TIMER in its > Kconfig. That's one optimization, not the issue of making the kernel more complicated. OK, I will add some kerneldoc to explain that. -- Baolin.wang Best Regards
next prev parent reply other threads:[~2018-02-14 3:49 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-02-06 10:36 [PATCH] arm64: Enable SPRD_TIMER Baolin Wang 2018-02-06 10:36 ` Baolin Wang 2018-02-07 2:31 ` Chunyan Zhang 2018-02-07 2:31 ` Chunyan Zhang 2018-02-07 3:12 ` Baolin Wang 2018-02-07 3:12 ` Baolin Wang 2018-02-11 11:41 ` Chunyan Zhang 2018-02-11 11:41 ` Chunyan Zhang 2018-02-14 3:49 ` Baolin Wang [this message] 2018-02-14 3:49 ` Baolin Wang
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