Re: [PATCH V2 0/4] Fix Incorrect State of Charge for RK817

[Lee Jones <lee@kernel.org>]

On Mon, 02 Nov 2026, Chris Morgan wrote:

> From: Chris Morgan <macromorgan@hotmail.com>
> 
> Users of the popular firmware RockNIX had identified a few bugs with
> accurately displaying the correct state of charge for RK817 battery
> devices. With the help of one user analyzing the code with Claude
> they were able to identify a few potential bugs along with potential
> solutions which I was then able to verify. These bugs are as follows:
> 
> 1) Incorrectly clamping a value with a max of 10000 instead of 100000.
> This bug caused the state of charge to sometimes read as 10% instead
> of 100% as it should have.
> 
> 2) Using the boot_voltage value to calibrate the battery in scenarios
> where it could not be trusted. The boot_voltage register populates
> immediately at power-on, and the driver would check if this value
> was older than 30 minutes before using it. Unfortunately when combined
> with the default behavior of the bootloader to turn the device off
> when plugged in (requiring a user to explicitly power the device on)
> the boot_voltage and boot_timer values were wrong. The boot voltage
> would not account for any voltage added while the device was off,
> and the boot_counter that tracks the time the device was off would
> be reset. To fix this we changed the behavior to (outside of first-boot
> scenarios) use a value saved to NVRAM, the value from the coulomb
> counter directly, and an OCV lookup from the live battery voltage,
> and then using those values provide an initial "guess" of the state
> of charge and recalibrate with the OCV voltage once it is available.
> 
> Included in this series is another fix that would cause the battery
> to drain while the system was shut down. This patch replicates the
> Rockchip BSP driver to clear a shutdown register. Unlike the BSP there
> is no behavior to bypass this since no boards have yet been observed
> using the SYS_CAN_SD bypass on the BSP kernel.
> 
> Changes Since V1:
>  - Dropped the sleep fixes, as I would like to test them a bit more
>    extensively first.
>  - Dropped the devicetree parameter, as since no boards have *yet*
>    needed to alter the default behavior there's no need for it.
>  - Changed the behavior of how we select the initial SOC and made
>    it its own function to ease in code readibility. This new method
>    was tested with various boot scenarios. The average error was less
>    than 5%, and in a worst case scenario where the device was
>    discharged to 0%, then left to charge at the bootloader the device
>    over-reported its state of charge by about 10%. When this occurred
>    the device reported its SOC as 100% but that it was charging, which
>    was corrected by the new OCV logic that kicked in once charging
>    completed.
>  - Scrapped the more complicated sleep fix in favor of simply telling
>    the battery to recalibrate at full after suspend, in case of a 
>    counting anomaly. 
> 
> Chris Morgan (4):
>   power: supply: rk817-charger: Fix NVRAM SoC Value
>   power: supply: rk817-charger: Resolve boot state of charge from the
>     coulomb counter
>   power: supply: rk817-charger: Clear SYS_CAN_SD register by default
>   power: supply: rk817-charger: Clear full charge cal on resume
> 
>  drivers/power/supply/rk817_charger.c | 313 ++++++++++++++++++++-------

>  include/linux/mfd/rk808.h            |   3 +

Acked-by: Lee Jones <lee@kernel.org>

>  2 files changed, 239 insertions(+), 77 deletions(-)

-- 
Lee Jones