linux-kernel - Re: [PATCH] cpufreq: imx6q: support frequencies >528MHz for i.MX6UL/ULL

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Date:   Mon, 12 Feb 2018 13:01:57 +0100
From:   Stefan Agner <stefan@...er.ch>
To:     "Rafael J. Wysocki" <rafael@...nel.org>, anson.huang@....com
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Fabio Estevam <fabio.estevam@....com>,
        Octavian Purdila <octavian.purdila@....com>,
        Shawn Guo <shawnguo@...nel.org>, max.oss.09@...il.com,
        marcel.ziswiler@...adex.com, Linux PM <linux-pm@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        rjwysocki@...il.com
Subject: Re: [PATCH] cpufreq: imx6q: support frequencies >528MHz for
 i.MX6UL/ULL

On 12.02.2018 11:18, Rafael J. Wysocki wrote:
> On Fri, Jan 19, 2018 at 12:58 AM, Stefan Agner <stefan@...er.ch> wrote:
>> Depending on SKU i.MX6UL/i.MX6ULL support frequencies up to 900MHz.
>> Use PLL1 sys clock for all operating points higher than 528MHz.
>>
>> Note: For higher operating points VDD_SOC_IN needs to be 125mV
>> higher than the ARM set-point (see datasheet). Specifically, the
>> i.MX6UL/ULL EVK boards have an external DC regulator which needs
>> adjustment. The regulator adjustment is not covered with this
>> change.
>>
>> Signed-off-by: Stefan Agner <stefan@...er.ch>
> 
> Can you please rebase this on top of 4.16-rc1?  It doesn't apply for me as is.
> 

Oh I see, Anson actually already submitted a patch which makes higher
CPU rates working.

My solution is slightly different in that it avoids unnecessary parent
changes...

I will rework this patch to apply this simplification to the current
state of the driver.

--
Stefan


>> ---
>>  drivers/cpufreq/imx6q-cpufreq.c | 14 ++++++++------
>>  1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
>> index 628fe899cb48..840f6386c780 100644
>> --- a/drivers/cpufreq/imx6q-cpufreq.c
>> +++ b/drivers/cpufreq/imx6q-cpufreq.c
>> @@ -114,12 +114,14 @@ static int imx6q_set_target(struct cpufreq_policy *policy, unsigned int index)
>>                  */
>>                 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 <= clk_get_rate(pll2_bus_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);
>> +               }
>>         } else {
>>                 clk_set_parent(step_clk, pll2_pfd2_396m_clk);
>>                 clk_set_parent(pll1_sw_clk, step_clk);
>> --
>> 2.15.1
>>