On Thu 07 Oct 10:28 PDT 2021, Ansuel Smith wrote:
> The function can loop and lock the system if for whatever reason the bit
> for the target sensor is NEVER valid. This is the case if a sensor is
> disabled by the factory and the valid bit is never reported as actually
> valid. Add a timeout check and exit if a timeout occurs. As this is
> a very rare condition, handle the timeout only if the first read fails.
> While at it also rework the function to improve readability and convert
> to poll_timeout generic macro.
>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Regards,
Bjorn
> Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>
> ---
> drivers/thermal/qcom/tsens.c | 29 ++++++++++++++---------------
> 1 file changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c
> index b1162e566a70..99a8d9f3e03c 100644
> --- a/drivers/thermal/qcom/tsens.c
> +++ b/drivers/thermal/qcom/tsens.c
> @@ -603,22 +603,21 @@ int get_temp_tsens_valid(const struct tsens_sensor *s, int *temp)
> int ret;
>
> /* VER_0 doesn't have VALID bit */
> - if (tsens_version(priv) >= VER_0_1) {
> - ret = regmap_field_read(priv->rf[valid_idx], &valid);
> - if (ret)
> - return ret;
> - while (!valid) {
> - /* Valid bit is 0 for 6 AHB clock cycles.
> - * At 19.2MHz, 1 AHB clock is ~60ns.
> - * We should enter this loop very, very rarely.
> - */
> - ndelay(400);
> - ret = regmap_field_read(priv->rf[valid_idx], &valid);
> - if (ret)
> - return ret;
> - }
> - }
> + if (tsens_version(priv) == VER_0)
> + goto get_temp;
> +
> + /* Valid bit is 0 for 6 AHB clock cycles.
> + * At 19.2MHz, 1 AHB clock is ~60ns.
> + * We should enter this loop very, very rarely.
> + * Wait 1 us since it's the min of poll_timeout macro.
> + * Old value was 400 ns.
> + */
> + ret = regmap_field_read_poll_timeout(priv->rf[valid_idx], valid,
> + valid, 1, 20 * USEC_PER_MSEC);
> + if (ret)
> + return ret;
>
> +get_temp:
> /* Valid bit is set, OK to read the temperature */
> *temp = tsens_hw_to_mC(s, temp_idx);
>
> --
> 2.32.0
>
