From: Anand Moon <linux.amoon@gmail.com>
To: Neil Armstrong <narmstrong@baylibre.com>
Cc: devicetree <devicetree@vger.kernel.org>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
Kevin Hilman <khilman@baylibre.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
linux-amlogic@lists.infradead.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Jerome Brunet <jbrunet@baylibre.com>
Subject: Re: [RFC-next 0/1] Odroid C2: Enable DVFS for cpu
Date: Tue, 10 Dec 2019 20:20:05 +0530 [thread overview]
Message-ID: <CANAwSgQx3LjQe60TGgKyk6B5BD5y1caS2tA+O+GFES7=qCFeKg@mail.gmail.com> (raw)
In-Reply-To: <c89791de-0a46-3ce2-b3e2-3640c364cd0f@baylibre.com>
Hi Neil / Kevin,
On Tue, 10 Dec 2019 at 14:13, Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> On 09/12/2019 23:12, Kevin Hilman wrote:
> > Anand Moon <linux.amoon@gmail.com> writes:
> >
> >> Some how this patch got lost, so resend this again.
> >>
> >> [0] https://patchwork.kernel.org/patch/11136545/
> >>
> >> This patch enable DVFS on GXBB Odroid C2.
> >>
> >> DVFS has been tested by running the arm64 cpuburn
> >> [1] https://github.com/ssvb/cpuburn-arm/blob/master/cpuburn-a53.S
> >> PM-QA testing
> >> [2] https://git.linaro.org/power/pm-qa.git [cpufreq testcase]
> >>
> >> Tested on latest U-Boot 2019.07-1 (Aug 01 2019 - 23:58:01 +0000) Arch Linux ARM
> >
> > Have you tested with the Harkernel u-boot?
> >
> > Last I remember, enabling CPUfreq will cause system hangs with the
> > Hardkernel u-boot because of improperly enabled frequencies, so I'm not
> > terribly inclined to merge this patch.
HK u-boot have many issue with loading the kernel, with load address
*it's really hard to build the kernel for HK u-boot*,
to get the configuration correctly.
Well I have tested with mainline u-boot with latest ATF .
I would prefer mainline u-boot for all the Amlogic SBC, since
they sync with latest driver changes.
>
> Same, since the bootloader boots with the max supported freq of the board,
> there is not real need of DVFS except for specific low-power use-cases.
>
> And still, some early boards still use the bad SCPI freq table, we can't break them.
>
> Neil
>
I will leave this to your expert domain knowledge if you want to
enable this now.
Here is output of on the latest kernel.
*cpupower*
# cpupower frequency-info
analyzing CPU 0:
driver: scpi-cpufreq
CPUs which run at the same hardware frequency: 0 1 2 3
CPUs which need to have their frequency coordinated by software: 0 1 2 3
maximum transition latency: 200 us
hardware limits: 100.0 MHz - 1.54 GHz
available frequency steps: 100.0 MHz, 250 MHz, 500 MHz, 1000 MHz,
1.30 GHz, 1.54 GHz
available cpufreq governors: conservative ondemand userspace
powersave performance schedutil
current policy: frequency should be within 100.0 MHz and 100.0 MHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency: 100.0 MHz (asserted by call to hardware)
*powertop*
# powertop
Package | CPU 0
100 MHz 47.1% | 100 MHz 41.5%
250 MHz 0.0% | 250 MHz 0.0%
500 MHz 0.0% | 500 MHz 0.0%
1000 MHz 0.0% | 1000 MHz 0.0%
1296 MHz 0.0% | 1296 MHz 0.0%
1.54 GHz 0.0% | 1.54 GHz 0.0%
Idle 52.9% | Idle 58.5%
> >
> >> Patch based on my next-20191031 for 5.5.x kernel.
> >> Hope this is not late entry.
> >
> > Re: "too late". FYI... when you post things as RFC, it means you're
> > looking for comments (Request For Comment) but that it's not intended
> > for merging.
Ok thanks for this input.
> >
> > I didn't see any comments on this, but I also didn't see a non-RFC
> > follow-up, so I didn't queue it for v5.5.
No problem.
> >
> > Kevin
> >
>
-Anand
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next prev parent reply other threads:[~2019-12-10 14:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-01 14:31 [RFC-next 0/1] Odroid C2: Enable DVFS for cpu Anand Moon
2019-11-01 14:31 ` [RFC-next 1/1] arm64: dts: meson: odroid-c2: Enable SCPI " Anand Moon
2019-12-09 22:12 ` [RFC-next 0/1] Odroid C2: Enable " Kevin Hilman
2019-12-10 8:43 ` Neil Armstrong
2019-12-10 14:50 ` Anand Moon [this message]
2019-12-10 18:13 ` Kevin Hilman
2019-12-10 20:04 ` Martin Blumenstingl
2019-12-10 21:47 ` Kevin Hilman
2019-12-11 8:49 ` Neil Armstrong
2019-12-12 20:09 ` Martin Blumenstingl
2019-12-13 11:28 ` Anand Moon
2019-12-13 13:24 ` Neil Armstrong
2019-12-13 14:23 ` Anand Moon
2020-01-02 0:16 ` Brad
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