[PATCH] arm64: dts: rockchip: Correct the Pinebook Pro battery design capacity

[Dragan Simic]

All batches of the Pine64 Pinebook Pro, except the latest batch (as of 2024)
whose hardware design was revised due to the component shortage, use a 1S
lithium battery whose nominal/design capacity is 10,000 mAh, according to the
battery datasheet. [1][2]  Let's correct the design full-charge value in the
Pinebook Pro board dts, to improve the accuracy of the hardware description,
and to hopefully improve the accuracy of the fuel gauge a bit on all units
that don't belong to the latest batch.

The above-mentioned latest batch uses a different 1S lithium battery with
a slightly lower capacity, more precisely 9,600 mAh.  To make the fuel gauge
work reliably on the latest batch, a sample battery would need to be sent to
CellWise, to obtain its proprietary battery profile, whose data goes into
"cellwise,battery-profile" in the Pinebook Pro board dts.  Without that data,
the fuel gauge reportedly works unreliably, so changing the design capacity
won't have any negative effects on the already unreliable operation of the
fuel gauge in the Pinebook Pros that belong to the latest batch.

According to the battery datasheet, its voltage can go as low as 2.75 V while
discharging, but it's better to leave the current 3.0 V value in the dts file,
because of the associated Pinebook Pro's voltage regulation issues.

[1] https://wiki.pine64.org/index.php/Pinebook_Pro#Battery
[2] https://files.pine64.org/doc/datasheet/pinebook/40110175P%203.8V%2010000mAh%E8%A7%84%E6%A0%BC%E4%B9%A6-14.pdf

Fixes: c7c4d698cd28 ("arm64: dts: rockchip: add fuel gauge to Pinebook Pro dts")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Marek Kraus <gamiee@xxxxxxxxxx>
Signed-off-by: Dragan Simic <dsimic@xxxxxxxxxxx>
---
 arch/arm64/boot/dts/rockchip/rk3399-pinebook-pro.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-pinebook-pro.dts b/arch/arm64/boot/dts/rockchip/rk3399-pinebook-pro.dts
index 294eb2de263d..c918968714e4 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-pinebook-pro.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3399-pinebook-pro.dts
@@ -37,7 +37,7 @@ backlight: edp-backlight {
 
 	bat: battery {
 		compatible = "simple-battery";
-		charge-full-design-microamp-hours = <9800000>;
+		charge-full-design-microamp-hours = <10000000>;
 		voltage-max-design-microvolt = <4350000>;
 		voltage-min-design-microvolt = <3000000>;
 	};