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From:   Kevin Hilman <khilman@baylibre.com>
To:     Anand Moon <linux.amoon@gmail.com>,
        Neil Armstrong <narmstrong@baylibre.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-amlogic@lists.infradead.org,
        Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC-next 0/1] Odroid C2: Enable DVFS for cpu
In-Reply-To: <CANAwSgQx3LjQe60TGgKyk6B5BD5y1caS2tA+O+GFES7=qCFeKg@mail.gmail.com>
References: <20191101143126.2549-1-linux.amoon@gmail.com> <7hfthtrvvv.fsf@baylibre.com> <c89791de-0a46-3ce2-b3e2-3640c364cd0f@baylibre.com> <CANAwSgQx3LjQe60TGgKyk6B5BD5y1caS2tA+O+GFES7=qCFeKg@mail.gmail.com>
Date:   Tue, 10 Dec 2019 10:13:18 -0800
Message-ID: <7hfthsqcap.fsf@baylibre.com>
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Sender: linux-kernel-owner@vger.kernel.org
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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.

Kevin