Re: [PATCH v2] ARM: dts: Add missing CPU frequencies for Exynos5422/5800
From: Javier Martinez Canillas
Date: Wed Jan 04 2017 - 18:58:11 EST
Hello Doug,
On 01/04/2017 06:05 PM, Doug Anderson wrote:
> Hi,
>
> On Thu, Dec 29, 2016 at 6:17 AM, Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
>> On Thu, Dec 15, 2016 at 04:54:30PM -0800, Doug Anderson wrote:
>>>> Index: b/arch/arm/boot/dts/exynos5800.dtsi
>>>> ===================================================================
>>>> --- a/arch/arm/boot/dts/exynos5800.dtsi 2016-12-15 12:43:54.365955950 +0100
>>>> +++ b/arch/arm/boot/dts/exynos5800.dtsi 2016-12-15 12:43:54.361955949 +0100
>>>> @@ -24,6 +24,16 @@
>>>> };
>>>>
>>>> &cluster_a15_opp_table {
>>>> + opp@2000000000 {
>>>> + opp-hz = /bits/ 64 <2000000000>;
>>>> + opp-microvolt = <1250000>;
>>>> + clock-latency-ns = <140000>;
>>>> + };
>>>> + opp@1900000000 {
>>>> + opp-hz = /bits/ 64 <1900000000>;
>>>> + opp-microvolt = <1250000>;
>>>> + clock-latency-ns = <140000>;
>>>> + };
>>>
>>> I don't think the voltages you listed are high enough for all peach pi
>>> boards for A15 at 1.9 GHz and 2.0 GHz, at least based on the research
>>> I did. See my response to v1.
>>
>> I wanted to apply this but saw this remaining issue. Javier tested it
>> on Peach Pi so is this concern still valid?
>
> I'm not sure. It's been years since I did anything with exynos, so I
> won't stand in the way if everyone else agrees that this patch is
> good, but I will point out that testing on a single Peach Pi board is
> not really enough given the massive difference in voltage needed
> between the highest ASV group and the lowest (a whopping 112.5 mV from
> looking in the Chrome OS source tree).
>
I agree. That's why answered that I wasn't able to find regressions on the
Peach Pi I've access to, but I couldn't provide a Reviewed-by tag since it
wasn't clear to me that the values were safe for any Exynos5420/5422/5800.
> -Doug
Best regards,
--
Javier Martinez Canillas
Open Source Group
Samsung Research America