[PATCH] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

[PATCH] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

[Ikjoon Jang]

Current sbs-battery considers all smbus errors as diconnection events
when battery-detect pin isn't supplied, and restored to present state back
on any successful transaction were made.

This can leads 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 well-known register to
check battery existence.

Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
---
 drivers/power/supply/sbs-battery.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
index 73461321eb05..483f814385a3 100644
--- a/drivers/power/supply/sbs-battery.c
+++ b/drivers/power/supply/sbs-battery.c
@@ -875,10 +875,17 @@ static int sbs_get_property(struct power_supply *psy,
 		return -EINVAL;
 	}
 
-	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:
@@ -1063,11 +1070,11 @@ 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);
-
-		if (rc < 0) {
-			dev_err(&client->dev, "%s: Failed to get device status\n",
-				__func__);
+		union power_supply_propval val;
+		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");
 			goto exit_psupply;
 		}
 	}
-- 
2.28.0.236.gb10cc79966-goog

Re: [PATCH] power: supply: sbs-battery: don't assume i2c errors as battery disconnect

[Nicolas Boichat]

On Mon, Aug 10, 2020 at 3:02 PM Ikjoon Jang <ikjn@chromium.org> wrote:
>
> Current sbs-battery considers all smbus errors as diconnection events
> when battery-detect pin isn't supplied, and restored to present state back
> on any successful transaction were made.
>
> This can leads 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 well-known register to
> check battery existence.
>
> Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
> ---
>  drivers/power/supply/sbs-battery.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
> index 73461321eb05..483f814385a3 100644
> --- a/drivers/power/supply/sbs-battery.c
> +++ b/drivers/power/supply/sbs-battery.c
> @@ -875,10 +875,17 @@ static int sbs_get_property(struct power_supply *psy,
>                 return -EINVAL;
>         }
>
> -       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));

No need for the !!: !ret && val.intval .

> +
> +               if (old_present != chip->is_present)
> +                       power_supply_changed(chip->power_supply);
>         }
>
>  done:
> @@ -1063,11 +1070,11 @@ 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);
> -
> -               if (rc < 0) {
> -                       dev_err(&client->dev, "%s: Failed to get device status\n",
> -                               __func__);
> +               union power_supply_propval val;
> +               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");
>                         goto exit_psupply;

sbs_get_battery_presence_and_health also reads
sbs_data[REG_STATUS].addr. That's good.

However, with psp == POWER_SUPPLY_PROP_PRESENT,
sbs_get_battery_presence_and_health always returns 0, but sets
val.intval = 0 in case of error.

This means that you goto exit_psupply with rc == 0, and sbs_probe does not fail.

I wonder if you should just drop this change, and use
sbs_read_word_data(client, sbs_data[REG_STATUS].addr); above, too.

>                 }
>         }
> --
> 2.28.0.236.gb10cc79966-goog
>