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Date: Thu, 3 Aug 2017 09:32:24 +0200
From: Sébastien Szymanski
<sebastien.szymanski@...adeus.com>
To: Shawn Guo <shawnguo@...nel.org>, Anson Huang <anson.huang@....com>,
Leonard Crestez <leonard.crestez@....com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
Viresh Kumar <viresh.kumar@...aro.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Julien Boibessot <julien.boibessot@...adeus.com>,
Fabio Estevam <fabio.estevam@....com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/1] cpufreq: imx6q: imx6ull: use PLL1 for frequency
higher than 528MHz
Hello,
On 08/03/2017 04:03 AM, Shawn Guo wrote:
> On Fri, Jul 28, 2017 at 10:36:33AM +0200, 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>
>
> Can you please specify on which SoCs you are seeing this problem? And I
> would like invite Anson and Leonard to review it.
My SoC is MCIMX6Y2CVM08AA which is a 792MHz i.MX6ULL. I forgot to
mention that I added the following operating points in my device tree:
operating-points: 792000 1225000
fsl,soc-operating-points: 792000 1175000
Best regards,
>
> Shawn
>
>> ---
>> drivers/cpufreq/imx6q-cpufreq.c | 11 +++++++++--
>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
>> index b6edd3c..e5fba50 100644
>> --- a/drivers/cpufreq/imx6q-cpufreq.c
>> +++ b/drivers/cpufreq/imx6q-cpufreq.c
>> @@ -18,6 +18,7 @@
>>
>> #define PU_SOC_VOLTAGE_NORMAL 1250000
>> #define PU_SOC_VOLTAGE_HIGH 1275000
>> +#define FREQ_528_MHZ 528000000
>> #define FREQ_1P2_GHZ 1200000000
>>
>> static struct regulator *arm_reg;
>> @@ -110,14 +111,20 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
>> * voltage of 528MHz, so lower the CPU frequency to one
>> * half before changing CPU frequency.
>> */
>> - clk_set_rate(arm_clk, (old_freq >> 1) * 1000);
>> - clk_set_parent(pll1_sw_clk, pll1_sys_clk);
>> + if ((old_freq * 1000) <= FREQ_528_MHZ) {
>> + clk_set_rate(arm_clk, (old_freq >> 1) * 1000);
>> + clk_set_parent(pll1_sw_clk, pll1_sys_clk);
>> + }
>> if (freq_hz > clk_get_rate(pll2_pfd2_396m_clk))
>> clk_set_parent(secondary_sel_clk, pll2_bus_clk);
>> else
>> clk_set_parent(secondary_sel_clk, pll2_pfd2_396m_clk);
>> clk_set_parent(step_clk, secondary_sel_clk);
>> clk_set_parent(pll1_sw_clk, step_clk);
>> + if (freq_hz > FREQ_528_MHZ) {
>> + clk_set_rate(pll1_sys_clk, freq_hz);
>> + clk_set_parent(pll1_sw_clk, pll1_sys_clk);
>> + }
>> } else {
>> clk_set_parent(step_clk, pll2_pfd2_396m_clk);
>> clk_set_parent(pll1_sw_clk, step_clk);
>> --
>> 2.7.3
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@...ts.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
Sébastien Szymanski
Software engineer, Armadeus Systems
Tel: +33 (0)9 72 29 41 44
Fax: +33 (0)9 72 28 79 26
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