Re: [PATCH 1/2] ARM: dts: rockchip: increase vdd_arm voltage for rk3066a-rayeager board

From: Eddie Cai <eddie.cai.kernel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Andy Yan <andy.yan-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
Cc: linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 1/2] ARM: dts: rockchip: increase vdd_arm voltage for rk3066a-rayeager board
Date: Thu, 14 Jan 2016 21:50:53 +0800	[thread overview]
Message-ID: <CANCyOWak0wMNRPxkJtE2DJ1UvCneWxuNXjwjxjM3+_Jjuaahvw@mail.gmail.com> (raw)
In-Reply-To: <5697A081.4060903-TNX95d0MmH7DzftRWevZcw@public.gmane.org>

Hi Heiko

I don't want open source version kernel support too high frequency.
Many people use RK3066/PX2 on their board. We don't know if their
layout is good enough to support higher frequency. ie. bad layout will
cause more voltage drop on the VDD_CPU power rail. So it may need
higher voltage. I think stable is more important here. People want
higher frequency can add more opp depend on their board's layout.

2016-01-14 21:20 GMT+08:00 Andy Yan <andy.yan@rock-chips.com>:
> Hi Heiko:
>
>
> On 2016年01月14日 20:45, Heiko Stuebner wrote:
>>
>> Hi Andy,
>>
>> Am Donnerstag, 14. Januar 2016, 20:34:20 schrieb Andy Yan:
>>>
>>> The current vdd_arm voltage is too low, increase it will make
>>> the system more stable.
>>>
>>> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
>>> ---
>>>
>>>   arch/arm/boot/dts/rk3066a-rayeager.dts | 8 ++++++++
>>>   1 file changed, 8 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/rk3066a-rayeager.dts
>>> b/arch/arm/boot/dts/rk3066a-rayeager.dts index 0bf6876..3d4c104 100644
>>> --- a/arch/arm/boot/dts/rk3066a-rayeager.dts
>>> +++ b/arch/arm/boot/dts/rk3066a-rayeager.dts
>>> @@ -159,6 +159,14 @@
>>>
>>>   &cpu0 {
>>>         cpu0-supply = <&vdd_arm>;
>>> +       operating-points = <
>>> +               /* kHz    uV */
>>> +               1008000 1125000
>>> +               816000  1125000
>>> +               600000  1100000
>>> +               504000  1100000
>>> +               312000  1075000
>>> +       >;
>>>   };
>>>
>>>   &emac {
>>
>> Does this only apply to the rayeager-board / px2 soc or for all
>> rk3066a/px2
>> boards? I.e. the original values come from some sdk kernel and I might've
>> transcribed that wrong at the time and I remember having problems trying
>> to
>> reach higher frequencies as well.
>>
>> So could you check what the full operating points looks like for both and
>> if
>> this can move to the rk3066a.dtsi, as both should be able to reach at
>> least
>> 1.4GHz / 1.6GHz.
>>
>>
>> Thanks
>> Heiko
>>
>> ______
>
>
>     I have checked the sdk kernel, the opp for the sdk board is like bellow:
>
>  /**
>  * dvfs_cpu_logic_table: table for arm and logic dvfs
>  * @frequency   : arm frequency
>  * @cpu_volt    : arm voltage depend on frequency
>  * @logic_volt  : logic voltage arm requests depend on frequency
>  * comments     : min arm/logic voltage
>  */
> static struct dvfs_arm_table dvfs_cpu_logic_table[] = {
>         {.frequency = 252 * 1000,       .cpu_volt = 1075 * 1000,
> .logic_volt = 1125 * 1000},//0.975V/1.000V
>         {.frequency = 504 * 1000,       .cpu_volt = 1100 * 1000,
> .logic_volt = 1125 * 1000},//0.975V/1.000V
>         {.frequency = 816 * 1000,       .cpu_volt = 1125 * 1000,
> .logic_volt = 1150 * 1000},//1.000V/1.025V
>         {.frequency = 1008 * 1000,      .cpu_volt = 1125 * 1000,
> .logic_volt = 1150 * 1000},//1.025V/1.050V
>         {.frequency = 1200 * 1000,      .cpu_volt = 1175 * 1000,
> .logic_volt = 1200 * 1000},//1.100V/1.050V
>         {.frequency = 1272 * 1000,      .cpu_volt = 1225 * 1000,
> .logic_volt = 1200 * 1000},//1.150V/1.100V
>         {.frequency = 1416 * 1000,      .cpu_volt = 1300 * 1000,
> .logic_volt = 1200 * 1000},//1.225V/1.100V
>         {.frequency = 1512 * 1000,      .cpu_volt = 1350 * 1000,
> .logic_volt = 1250 * 1000},//1.300V/1.150V
>         {.frequency = 1608 * 1000,      .cpu_volt = 1425 * 1000,
> .logic_volt = 1300 * 1000},//1.325V/1.175V
>         {.frequency = CPUFREQ_TABLE_END},
> };
>
>  This table is made base on mass stress test. So is a safe opp table for
> most rk3066a base boards. But it some
>  board is not so well in power supply circuit design, the may also need to
> adjust it.
>
>  From the table we see that the logic_voltage need to increase  as the
> cpufreq increase. But it seems that the current mainline kernel does not
> support adjust the logic voltage when cpufreq change. So we can only scale
> the cpufreq to 1.4GHZ by fixed the logic_volt at 1.2V.
>
>  If you like, I can move it to rk3066a.dtsi with the max freq at 1008MHZ, as
> I haven't  test to 1.4GHZ  with the mainline kernel. Or give me some time to
> test to see if the rayeager board can run to 1.4G stable with the mainline .
>
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>
>
>
>
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