linux-kernel - Re: [PATCH 1/1] cpufreq: imx6q: imx6ull: use PLL1 for frequency higher than 528MHz

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Message-ID: <20170802034951.GA31169@vireshk-i7>
Date:   Wed, 2 Aug 2017 09:19:51 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Shawn Guo <shawnguo@...nel.org>,
        Sébastien Szymanski 
        <sebastien.szymanski@...adeus.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Fabio Estevam <fabio.estevam@....com>,
        Julien Boibessot <julien.boibessot@...adeus.com>
Subject: Re: [PATCH 1/1] cpufreq: imx6q: imx6ull: use PLL1 for frequency
 higher than 528MHz

On 28-07-17, 10:36, Sébastien Szymanski wrote:
> Setting the frequency higher than 528Mhz actually sets the ARM
> clock to 528MHz. That's because PLL2 is used as the root clock when the
> frequency is higher than 396MHz.
> 
> cpupower frequency-set -f 792000
> 
> arm_clk_root on the CCM_CLKO2 signal is 528MHz instead of 792MHz.
> 
> [   61.606383] cpu cpu0: 396 MHz, 1025 mV --> 792 MHz, 1225 mV
> 
> pll2                         1  1  528000000 0 0
>    pll2_bypass               1  1  528000000 0 0
>       pll2_bus               3  3  528000000 0 0
> 	 ca7_secondary_sel   1  1  528000000 0 0
> 	    step             1  1  528000000 0 0
> 	       pll1_sw       1  1  528000000 0 0
> 		  arm        1  1  528000000 0 0
> 
> Fixes this by using the PLL1 as the root clock when the frequency is
> higher than 528MHz.
> 
> cpupower frequency-set -f 792000
> 
> arm_clk_root on the CCM_CLKO2 signal is now 792MHz as expected.
> 
> [   69.717987] cpu cpu0: 198 MHz, 950 mV --> 792 MHz, 1225 mV
> 
> pll1               1 1 792000000 0 0
>    pll1_bypass     1 1 792000000 0 0
>       pll1_sys     1 1 792000000 0 0
> 	 pll1_sw   1 1 792000000 0 0
> 	    arm    1 1 792000000 0 0
> 
> Signed-off-by: Sébastien Szymanski <sebastien.szymanski@...adeus.com>
> ---
>  drivers/cpufreq/imx6q-cpufreq.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)

Looks fine to me:

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

@Shawn: Can you also confirm if this looks fine to you ?

-- 
viresh