Hi Javier,
On 2017-01-24 18:57, Javier Martinez Canillas wrote:
Hello Krzysztof,
On 01/24/2017 02:52 PM, Krzysztof Kozlowski wrote:
On Tue, Jan 24, 2017 at 01:45:28PM +0100, Andrzej Hajda wrote:
LDO7 regulator beside DSI and HDMI provides power for core blocks in Exynos
5433 SoC. Disabling it causes serious current leak - about 200mA.
Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
---
arch/arm64/boot/dts/exynos/exynos5433-tm2-common.dtsi | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/boot/dts/exynos/exynos5433-tm2-common.dtsi b/arch/arm64/boot/dts/exynos/exynos5433-tm2-common.dtsi
index 5f1e172..b22bec8 100644
--- a/arch/arm64/boot/dts/exynos/exynos5433-tm2-common.dtsi
+++ b/arch/arm64/boot/dts/exynos/exynos5433-tm2-common.dtsi
@@ -432,6 +432,10 @@
regulator-name = "VDD18_MIPI2L_1.8V_AP";
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
I see you already applied, but I think it would be good to have some comments
here explaining why the regulator should be always-on. Otherwise, in future a
developer might want to disable the regulator since it may think that is not
needed due dsi and hdmi already enabling it.
If such change is added in a separate commit, one can easily find the reason
using "git blame".
+ regulator-always-on;
+ regulator-state-mem {
+ regulator-off-in-suspend;
+ };
Thanks, applied.
Just to satisfy my curiosity, how disabling the regulator causes current
leak? What happens exactly?
Such leakage usually happens if there is a hw block, which have more
than one
power supply. Disabling power for the one power supply might turn the hw
logic
into some meta state, in which it still conduct a current from the other
source.
The best example of such behavior is Odroid U3 and its problems with
reset when
HDMI cable is connected. Sometimes the current leaks from the HDMI
connector to
the board when the main power supply is turned off and the board enters some
kind of a a "meta state".
We still have no idea which hw block causes this leakage in case of TM2/TM2e
though.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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