Re: [RFC-next 0/1] Odroid C2: Enable DVFS for cpu

From: Kevin Hilman <khilman@baylibre.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: devicetree <devicetree@vger.kernel.org>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Anand Moon <linux.amoon@gmail.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 13:47:09 -0800	[thread overview]
Message-ID: <7hpngvontu.fsf@baylibre.com> (raw)
In-Reply-To: <CAFBinCBfgxXhPKpBLdoq9AimrpaneYFgzgJoDyC-2xhbHmihpA@mail.gmail.com>

Martin Blumenstingl <martin.blumenstingl@googlemail.com> writes:

> On Tue, Dec 10, 2019 at 7:13 PM Kevin Hilman <khilman@baylibre.com> wrote:
>>
>> Anand Moon <linux.amoon@gmail.com> writes:
>>
>> > 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.
>>
>> Yes, we would all prefer mainline u-boot, but the mainline kernel needs
>> to support the vendor u-boot that is shipping with the boards.  So
>> until Hardkernel (and other vendors) switch to mainline u-boot we do not
>> want to have upstream kernel defaults that will not boot with the vendor
>> u-boot.
>>
>> We can always support these features, but they just cannot be enabled
>> by default.
> (I don't have an Odroid-C2 but I'm curious)
> should Anand submit a patch to mainline u-boot instead?

It would be in addition to $SUBJECT patch, not instead, I think.

> the &scpi_clocks node could be enabled at runtime by mainline u-boot

That would work, but I don't know about u-boot maintainers opinions on
this kind of thing, so let's see what Neil thinks.

Kevin

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