ECs implementing the v2 command will not stop charging when the end threshold is reached. Instead they will begin discharging until the start threshold is reached, leading to permanent charge and discharge cycles. This defeats the point of the charge control mechanism.
Avoid the issue by hiding the start threshold on v2 systems. Instead on those systems program the EC with start == end which forces the EC to reach and stay at that level.
v1 does not support thresholds and v3 works correctly, at least judging from the code.
Reported-by: Thomas Koch linrunner@gmx.net Fixes: c6ed48ef5259 ("power: supply: add ChromeOS EC based charge control driver") Cc: stable@vger.kernel.org Signed-off-by: Thomas Weißschuh linux@weissschuh.net --- drivers/power/supply/cros_charge-control.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/power/supply/cros_charge-control.c b/drivers/power/supply/cros_charge-control.c index 108b121db4423187fb65548396fb9195b8801006..9b0a7500296b4d7eb8cd53153e148926bb98aec1 100644 --- a/drivers/power/supply/cros_charge-control.c +++ b/drivers/power/supply/cros_charge-control.c @@ -139,6 +139,10 @@ static ssize_t cros_chctl_store_threshold(struct device *dev, struct cros_chctl_ return -EINVAL;
if (is_end_threshold) { + /* Start threshold is not exposed, use fixed value */ + if (priv->cmd_version == 2) + priv->current_start_threshold = val == 100 ? 0 : val; + if (val < priv->current_start_threshold) return -EINVAL; priv->current_end_threshold = val; @@ -234,12 +238,10 @@ static umode_t cros_chtl_attr_is_visible(struct kobject *kobj, struct attribute { struct cros_chctl_priv *priv = cros_chctl_attr_to_priv(attr, n);
- if (priv->cmd_version < 2) { - if (n == CROS_CHCTL_ATTR_START_THRESHOLD) - return 0; - if (n == CROS_CHCTL_ATTR_END_THRESHOLD) - return 0; - } + if (n == CROS_CHCTL_ATTR_START_THRESHOLD && priv->cmd_version < 3) + return 0; + else if (n == CROS_CHCTL_ATTR_END_THRESHOLD && priv->cmd_version < 2) + return 0;
return attr->mode; }