2015-08-04 21:08:33

by Timo Sigurdsson

[permalink] [raw]
Subject: [PATCH v2] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to meet SoC specifications

sun7i-a20.dtsi contains a cpufreq operating point at 0.9 volts. The minimum
CPU voltage for the Allwinner A20 SoC, however, is 1.0 volts. Thus, raise
the voltage for the lowest operating point to 1.0 volts in order to stay
within the SoC specifications. It is an undervolted setting that isn't
stable across all SoCs and boards out there.

Signed-off-by: Timo Sigurdsson <[email protected]>
---
Changes since v1:

- Fixed checkpatch warnings
- Changed the commit message and title to clarify that this is not a board-specific issue, but rather a limitation by the SoC
---
arch/arm/boot/dts/sun7i-a20.dtsi | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
index 6a63f30..f5f384c 100644
--- a/arch/arm/boot/dts/sun7i-a20.dtsi
+++ b/arch/arm/boot/dts/sun7i-a20.dtsi
@@ -107,7 +107,7 @@
720000 1200000
528000 1100000
312000 1000000
- 144000 900000
+ 144000 1000000
>;
#cooling-cells = <2>;
cooling-min-level = <0>;
--
2.1.4


2015-08-09 22:59:01

by Iain Paton

[permalink] [raw]
Subject: Re: [linux-sunxi] [PATCH v2] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to meet SoC specifications

Acked-by: Iain Paton <[email protected]>

On 04/08/15 22:08, Timo Sigurdsson wrote:
> sun7i-a20.dtsi contains a cpufreq operating point at 0.9 volts. The minimum
> CPU voltage for the Allwinner A20 SoC, however, is 1.0 volts. Thus, raise
> the voltage for the lowest operating point to 1.0 volts in order to stay
> within the SoC specifications. It is an undervolted setting that isn't
> stable across all SoCs and boards out there.
>
> Signed-off-by: Timo Sigurdsson <[email protected]>
> ---
> Changes since v1:
>
> - Fixed checkpatch warnings
> - Changed the commit message and title to clarify that this is not a board-specific issue, but rather a limitation by the SoC
> ---
> arch/arm/boot/dts/sun7i-a20.dtsi | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
> index 6a63f30..f5f384c 100644
> --- a/arch/arm/boot/dts/sun7i-a20.dtsi
> +++ b/arch/arm/boot/dts/sun7i-a20.dtsi
> @@ -107,7 +107,7 @@
> 720000 1200000
> 528000 1100000
> 312000 1000000
> - 144000 900000
> + 144000 1000000
> >;
> #cooling-cells = <2>;
> cooling-min-level = <0>;
>

2015-08-17 15:18:55

by Maxime Ripard

[permalink] [raw]
Subject: Re: [PATCH v2] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to meet SoC specifications

Hi Timo,

On Tue, Aug 04, 2015 at 11:08:01PM +0200, Timo Sigurdsson wrote:
> sun7i-a20.dtsi contains a cpufreq operating point at 0.9 volts. The minimum
> CPU voltage for the Allwinner A20 SoC, however, is 1.0 volts. Thus, raise
> the voltage for the lowest operating point to 1.0 volts in order to stay
> within the SoC specifications. It is an undervolted setting that isn't
> stable across all SoCs and boards out there.
>
> Signed-off-by: Timo Sigurdsson <[email protected]>

Added Iain's Ack, and Cc stable

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com


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