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SubjectRe: [PATCH 3/3] power: supply: max17040: Set rcomp value
Hi,

On Mon, May 04, 2020 at 03:13:00PM -0700, Jonathan Bakker wrote:
> According to the datasheet (1), the rcomp parameter can
> vary based on the typical operating temperature and the
> battery chemistry. If provided, make sure we set it after
> we reset the chip on boot.
>
> 1) https://datasheets.maximintegrated.com/en/ds/MAX17040-MAX17041.pdf
>
> Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
> ---
> drivers/power/supply/max17040_battery.c | 33 +++++++++++++++++++++----
> 1 file changed, 28 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/power/supply/max17040_battery.c b/drivers/power/supply/max17040_battery.c
> index 48aa44665e2f..f66e2fdc0a8a 100644
> --- a/drivers/power/supply/max17040_battery.c
> +++ b/drivers/power/supply/max17040_battery.c
> @@ -10,6 +10,7 @@
> #include <linux/init.h>
> #include <linux/platform_device.h>
> #include <linux/mutex.h>
> +#include <linux/property.h>
> #include <linux/err.h>
> #include <linux/i2c.h>
> #include <linux/delay.h>
> @@ -31,6 +32,8 @@
>
> #define MAX17040_ATHD_MASK 0xFFC0
> #define MAX17040_ATHD_DEFAULT_POWER_UP 4
> +#define MAX17040_RCOMP_MASK 0xFF
> +#define MAX17040_RCOMP_DEFAULT_POWER_UP 0x97

Why is this 8 bits? Quote from the datasheet, that you linked:

»RCOMP is a 16-bit value used to compensate the ModelGauge algorithm«

-- Sebastian

> struct max17040_chip {
> struct i2c_client *client;
> @@ -48,6 +51,8 @@ struct max17040_chip {
> int status;
> /* Low alert threshold from 32% to 1% of the State of Charge */
> u32 low_soc_alert;
> + /* Optimization for specific chemistries */
> + u8 rcomp_value;
> };
>
> static int max17040_get_property(struct power_supply *psy,
> @@ -119,6 +124,20 @@ static int max17040_set_low_soc_alert(struct i2c_client *client, u32 level)
> return ret;
> }
>
> +static int max17040_set_rcomp(struct i2c_client *client, u32 val)
> +{
> + int ret;
> + u16 data;
> +
> + data = max17040_read_reg(client, MAX17040_RCOMP);
> + /* clear the rcomp val and set MSb 8 bits */
> + data &= MAX17040_RCOMP_MASK;
> + data |= val << 8;
> + ret = max17040_write_reg(client, MAX17040_RCOMP, data);
> +
> + return ret;
> +}
> +
> static void max17040_get_vcell(struct i2c_client *client)
> {
> struct max17040_chip *chip = i2c_get_clientdata(client);
> @@ -190,8 +209,14 @@ static int max17040_get_of_data(struct max17040_chip *chip)
> "maxim,alert-low-soc-level",
> &chip->low_soc_alert);
>
> - if (chip->low_soc_alert <= 0 || chip->low_soc_alert >= 33)
> + if (chip->low_soc_alert <= 0 || chip->low_soc_alert >= 33) {
> + dev_err(&client->dev,
> + "failed: low SOC alert OF data out of bounds\n");
> return -EINVAL;
> + }
> +
> + chip->rcomp_value = MAX17040_RCOMP_DEFAULT_POWER_UP;
> + device_property_read_u8(dev, "maxim,rcomp-value", &chip->rcomp_value);
>
> return 0;
> }
> @@ -289,11 +314,8 @@ static int max17040_probe(struct i2c_client *client,
> chip->client = client;
> chip->pdata = client->dev.platform_data;
> ret = max17040_get_of_data(chip);
> - if (ret) {
> - dev_err(&client->dev,
> - "failed: low SOC alert OF data out of bounds\n");
> + if (ret)
> return ret;
> - }
>
> i2c_set_clientdata(client, chip);
> psy_cfg.drv_data = chip;
> @@ -307,6 +329,7 @@ static int max17040_probe(struct i2c_client *client,
>
> max17040_reset(client);
> max17040_get_version(client);
> + max17040_set_rcomp(client, chip->rcomp_value);
>
> /* check interrupt */
> if (client->irq && of_device_is_compatible(client->dev.of_node,
> --
> 2.20.1
>
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