linux-kernel - Re: [PATCH v3 2/2] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

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Message-ID: <20200827220010.tq5564p3ysebmtwu@earth.universe>
Date:   Fri, 28 Aug 2020 00:00:10 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Ikjoon Jang <ikjn@...omium.org>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        drinkcat@...omium.org
Subject: Re: [PATCH v3 2/2] power: supply: sbs-battery: don't assume i2c
 errors as battery disconnect

Hi,

On Thu, Aug 13, 2020 at 01:10:08PM +0800, Ikjoon Jang wrote:
> Current sbs-battery considers all smbus errors as disconnection events
> when battery-detect pin isn't supplied, and restored to present state back
> when any successful transaction is made.
> 
> This can lead to unlimited state changes between present and !present
> when one unsupported command was requested and other following commands
> were successful, e.g. udev rules tries to read multiple properties.
> 
> This patch checks battery presence by reading known good command to
> check battery existence.
> 
> Signed-off-by: Ikjoon Jang <ikjn@...omium.org>
> ---

Does not apply, please rebase. Also we probably should add
another compatible value for your specific chip not supporting
some properties, so that they are not exposed?

-- Sebastian

>  drivers/power/supply/sbs-battery.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
> index 6acb4ea25d2a..2e32fde04628 100644
> --- a/drivers/power/supply/sbs-battery.c
> +++ b/drivers/power/supply/sbs-battery.c
> @@ -878,10 +878,17 @@ static int sbs_get_property(struct power_supply *psy,
>  	if (!chip->enable_detection)
>  		goto done;
>  
> -	if (!chip->gpio_detect &&
> -		chip->is_present != (ret >= 0)) {
> -		sbs_update_presence(chip, (ret >= 0));
> -		power_supply_changed(chip->power_supply);
> +	if (!chip->gpio_detect && chip->is_present != (ret >= 0)) {
> +		bool old_present = chip->is_present;
> +		union power_supply_propval val;
> +
> +		ret = sbs_get_battery_presence_and_health(
> +				client, POWER_SUPPLY_PROP_PRESENT, &val);
> +
> +		sbs_update_presence(chip, !ret && val.intval);
> +
> +		if (old_present != chip->is_present)
> +			power_supply_changed(chip->power_supply);
>  	}
>  
>  done:
> @@ -1067,11 +1074,13 @@ static int sbs_probe(struct i2c_client *client)
>  	 * to the battery.
>  	 */
>  	if (!(force_load || chip->gpio_detect)) {
> -		rc = sbs_read_word_data(client, sbs_data[REG_STATUS].addr);
> +		union power_supply_propval val;
>  
> -		if (rc < 0) {
> -			dev_err(&client->dev, "%s: Failed to get device status\n",
> -				__func__);
> +		rc = sbs_get_battery_presence_and_health(
> +				client, POWER_SUPPLY_PROP_PRESENT, &val);
> +		if (rc < 0 || !val.intval) {
> +			dev_err(&client->dev, "Failed to get present status\n");
> +			rc = -ENODEV;
>  			goto exit_psupply;
>  		}
>  	}
> -- 
> 2.28.0.236.gb10cc79966-goog
> 

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