Re: [PATCH RESEND v6 15/17] power: supply: bd71828: Support wider register addresses

Sebastian Reichel
2026-01-12T00:46:28Z

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Hi,

On Mon, Dec 15, 2025 at 03:21:03PM +0200, Matti Vaittinen wrote:
> From: Matti Vaittinen <mazziesaccount@gmail.com>
>
> The BD71828 power-supply driver assumes register addresses to be 8-bit.
> The new BD72720 will use stacked register maps to hide paging which is
> done using secondary I2C slave address. This requires use of 9-bit
> register addresses in the power-supply driver (added offset 0x100 to
> the 8-bit hardware register addresses).
>
> The cost is slightly used memory consumption as the members in the
> struct pwr_regs will be changed from u8 to unsigned int, which means 3
> byte increase / member / instance.
> This is currently 14 members (expected to possibly be increased when
> adding new variants / new functionality which may introduce new
> registers, but not expected to grow much) and 2 instances (will be 3
> instances when BD72720 gets added).
>
> So, even if the number of registers grew to 50 it'd be 150 bytes /
> instance. Assuming we eventually supported 5 variants, it'd be
> 5 * 150 bytes, which stays very reasonable considering systems we are
> dealing with.
>
> As a side note, we can reduce the "wasted space / member / instance" from
> 3 bytes to 1 byte, by using u16 instead of the unsigned int if needed. I
> rather use unsigned int to be initially prepared for devices with 32 bit
> registers if there is no need to count bytes.
>
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Greetings,

-- Sebastian

> Revision history:
> v2 => :
> - No changes
>
> RFCv1 => v2:
> - New patch
> ---
> drivers/power/supply/bd71828-power.c | 26 +++++++++++++-------------
> 1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/power/supply/bd71828-power.c b/drivers/power/supply/bd71828-power.c
> index f667baedeb77..ce73c0f48397 100644
> --- a/drivers/power/supply/bd71828-power.c
> +++ b/drivers/power/supply/bd71828-power.c
> @@ -44,19 +44,19 @@
> #define VBAT_LOW_TH 0x00D4
>
> struct pwr_regs {
> - u8 vbat_avg;
> - u8 ibat;
> - u8 ibat_avg;
> - u8 btemp_vth;
> - u8 chg_state;
> - u8 bat_temp;
> - u8 dcin_stat;
> - u8 dcin_collapse_limit;
> - u8 chg_set1;
> - u8 chg_en;
> - u8 vbat_alm_limit_u;
> - u8 conf;
> - u8 vdcin;
> + unsigned int vbat_avg;
> + unsigned int ibat;
> + unsigned int ibat_avg;
> + unsigned int btemp_vth;
> + unsigned int chg_state;
> + unsigned int bat_temp;
> + unsigned int dcin_stat;
> + unsigned int dcin_collapse_limit;
> + unsigned int chg_set1;
> + unsigned int chg_en;
> + unsigned int vbat_alm_limit_u;
> + unsigned int conf;
> + unsigned int vdcin;
> };
>
> static const struct pwr_regs pwr_regs_bd71828 = {
> --
> 2.52.0
>

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