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Subject: Re: [PATCH v2 0/7] cpufreq support for Raspberry Pi
To:     Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        linux-kernel@vger.kernel.org
Cc:     mbrugger@suse.de, viresh.kumar@linaro.org, rjw@rjwysocki.net,
        sboyd@kernel.org, eric@anholt.net, f.fainelli@gmail.com,
        bcm-kernel-feedback-list@broadcom.com, ptesarik@suse.com,
        linux-rpi-kernel@lists.infradead.org, ssuloev@orpaltech.com,
        linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        mturquette@baylibre.com, linux-pm@vger.kernel.org
References: <20190606142255.29454-1-nsaenzjulienne@suse.de>
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Date:   Sat, 8 Jun 2019 12:43:18 +0200
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Am 06.06.19 um 16:22 schrieb Nicolas Saenz Julienne:
> Hi all,
> this aims at adding cpufreq support to the Raspberry Pi family of
> boards.
>
> The series first factors out 'pllb' from clk-bcm2385 and creates a new
> clk driver that operates it over RPi's firmware interface[1]. We are
> forced to do so as the firmware 'owns' the pll and we're not allowed to
> change through the register interface directly as we might race with the
> over-temperature and under-voltage protections provided by the firmware.
>
> Next it creates a minimal cpufreq driver that populates the CPU's opp
> table, and registers cpufreq-dt. Which is needed as the firmware
> controls the max and min frequencies available.

Here some figures from the Raspberry Pi 3 B+ as before/after comparison:

Dhrystone Benchmark 2.1 A7 32 Bit

 600 MHz, w/o Turbo (1): 1216.11 VAX MIPS
1400 MHz, w/o Turbo (2): 2839.67 VAX MIPS
1400 MHz, w   Turbo (3): 2839.45 VAX MIPS

Whetstone Single Precision C Benchmark  vfpv4 32 Bit

 600 MHz, w/o Turbo: 454.565 MWIPS
1400 MHz, w/o Turbo: 1062.494 MWIPS
1400 MHz, w   Turbo: 1061.723 MWIPS

Power consumption (32 bit, without Ethernet) with load ( cat /dev/zero )

 600 MHz, w/o Turbo: 2.48 W
1400 MHz, w/o Turbo: 3.2 W
1400 MHz, w   Turbo: 3.15 W

Note 1: This is the maximum performance before enabling any cpufreq driver.

Note 2: This is the maximum performance after enabling V2 of the cpufreq
driver
http://lists.infradead.org/pipermail/linux-arm-kernel/2019-June/657768.html

Note 3: This is the maximum performance after enabling the initial
cpufreq driver
http://lists.infradead.org/pipermail/linux-rpi-kernel/2019-April/008634.html