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Message-ID: <20170615164353.suitnkeiaorkj6cz@earth>
Date: Thu, 15 Jun 2017 18:43:53 +0200
From: Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To: Shawn Nematbakhsh <shawnn@...omium.org>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
groeck@...omium.org
Subject: Re: [PATCH 1/2] power: supply: sbs-battery: Prevent CAPACITY_MODE
races
Hi,
On Tue, Jun 13, 2017 at 10:53:25AM -0700, Shawn Nematbakhsh wrote:
> A subset of smart battery commands return charge or energy depending on
> the CAPACITY_MODE bit setting of BatteryMode(). In order to
> unambiguously read a charge or energy value, it is necessary to ensure
> that CAPACITY_MODE is set as desired, and not changed for the duration
> of the attribute read.
>
> Signed-off-by: Shawn Nematbakhsh <shawnn@...omium.org>
> ---
Thanks, queued.
-- Sebastian
> drivers/power/supply/sbs-battery.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/power/supply/sbs-battery.c b/drivers/power/supply/sbs-battery.c
> index e3a114e60f1a..d7e68fd97099 100644
> --- a/drivers/power/supply/sbs-battery.c
> +++ b/drivers/power/supply/sbs-battery.c
> @@ -171,6 +171,7 @@ struct sbs_info {
> u32 i2c_retry_count;
> u32 poll_retry_count;
> struct delayed_work work;
> + struct mutex mode_lock;
> };
>
> static char model_name[I2C_SMBUS_BLOCK_MAX + 1];
> @@ -623,7 +624,13 @@ static int sbs_get_property(struct power_supply *psy,
> if (ret < 0)
> break;
>
> + /* sbs_get_battery_capacity() will change the battery mode
> + * temporarily to read the requested attribute. Ensure we stay
> + * in the desired mode for the duration of the attribute read.
> + */
> + mutex_lock(&chip->mode_lock);
> ret = sbs_get_battery_capacity(client, ret, psp, val);
> + mutex_unlock(&chip->mode_lock);
> break;
>
> case POWER_SUPPLY_PROP_SERIAL_NUMBER:
> @@ -808,6 +815,7 @@ static int sbs_probe(struct i2c_client *client,
> psy_cfg.of_node = client->dev.of_node;
> psy_cfg.drv_data = chip;
> chip->last_state = POWER_SUPPLY_STATUS_UNKNOWN;
> + mutex_init(&chip->mode_lock);
>
> /* use pdata if available, fall back to DT properties,
> * or hardcoded defaults if not
> --
> 2.13.1.508.gb3defc5cc-goog
>
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