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SubjectRe: [PATCH 3/3] hwmon: bt1-pvt: Wait for the completion with timeout
On Sun, Sep 20, 2020 at 02:09:23PM +0300, Serge Semin wrote:
> If the PVT sensor is suddenly powered down while a caller is waiting for
> the conversion completion, the request won't be finished and the task will
> hang up on this procedure until the power is back up again. Let's call the
> wait_for_completion_timeout() method instead to prevent that. The cached
> timeout is exactly what we need to predict for how long conversion could
> normally last.
>
> Fixes: 87976ce2825d ("hwmon: Add Baikal-T1 PVT sensor driver")
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>

Applied.

Thanks,
Guenter

> ---
> drivers/hwmon/bt1-pvt.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/bt1-pvt.c b/drivers/hwmon/bt1-pvt.c
> index 2600426a3b21..3e1d56585b91 100644
> --- a/drivers/hwmon/bt1-pvt.c
> +++ b/drivers/hwmon/bt1-pvt.c
> @@ -477,6 +477,7 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
> long *val)
> {
> struct pvt_cache *cache = &pvt->cache[type];
> + unsigned long timeout;
> u32 data;
> int ret;
>
> @@ -500,7 +501,14 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
> pvt_update(pvt->regs + PVT_INTR_MASK, PVT_INTR_DVALID, 0);
> pvt_update(pvt->regs + PVT_CTRL, PVT_CTRL_EN, PVT_CTRL_EN);
>
> - wait_for_completion(&cache->conversion);
> + /*
> + * Wait with timeout since in case if the sensor is suddenly powered
> + * down the request won't be completed and the caller will hang up on
> + * this procedure until the power is back up again. Multiply the
> + * timeout by the factor of two to prevent a false timeout.
> + */
> + timeout = 2 * usecs_to_jiffies(ktime_to_us(pvt->timeout));
> + ret = wait_for_completion_timeout(&cache->conversion, timeout);
>
> pvt_update(pvt->regs + PVT_CTRL, PVT_CTRL_EN, 0);
> pvt_update(pvt->regs + PVT_INTR_MASK, PVT_INTR_DVALID,
> @@ -510,6 +518,9 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
>
> mutex_unlock(&pvt->iface_mtx);
>
> + if (!ret)
> + return -ETIMEDOUT;
> +
> if (type == PVT_TEMP)
> *val = pvt_calc_poly(&poly_N_to_temp, data);
> else

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