From: Guenter Roeck <linux@roeck-us.net>
To: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Jean Delvare <jdelvare@suse.com>,
Serge Semin <fancer.lancer@gmail.com>,
kbuild test robot <lkp@intel.com>,
Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] hwmon: bt1-pvt: Declare Temp- and Volt-to-N poly when alarms are enabled
Date: Tue, 2 Jun 2020 07:07:46 -0700 [thread overview]
Message-ID: <20200602140746.GA82514@roeck-us.net> (raw)
In-Reply-To: <20200602091219.24404-1-Sergey.Semin@baikalelectronics.ru>
On Tue, Jun 02, 2020 at 12:12:19PM +0300, Serge Semin wrote:
> Clang-based kernel building with W=1 warns that some static const
> variables are unused:
>
> drivers/hwmon/bt1-pvt.c:67:30: warning: unused variable 'poly_temp_to_N' [-Wunused-const-variable]
> static const struct pvt_poly poly_temp_to_N = {
> ^
> drivers/hwmon/bt1-pvt.c:99:30: warning: unused variable 'poly_volt_to_N' [-Wunused-const-variable]
> static const struct pvt_poly poly_volt_to_N = {
> ^
>
> Indeed these polynomials are utilized only when the PVT sensor alarms are
> enabled. In that case they are used to convert the temperature and
> voltage alarm limits from normal quantities (Volts and degree Celsius) to
> the sensor data representation N = [0, 1023]. Otherwise when alarms are
> disabled the driver only does the detected data conversion to the human
> readable form and doesn't need that polynomials defined. So let's declare
> the Temp-to-N and Volt-to-N polynomials only if the PVT alarms are
> switched on at compile-time.
>
> Note gcc with W=1 doesn't notice the problem.
>
> Fixes: 87976ce2825d ("hwmon: Add Baikal-T1 PVT sensor driver")
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Cc: Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
I don't really like the added #if. Can you use __maybe_unused instead ?
Thanks,
Guenter
> ---
> drivers/hwmon/bt1-pvt.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hwmon/bt1-pvt.c b/drivers/hwmon/bt1-pvt.c
> index 1a9772fb1f73..1a5212c04549 100644
> --- a/drivers/hwmon/bt1-pvt.c
> +++ b/drivers/hwmon/bt1-pvt.c
> @@ -64,6 +64,7 @@ static const struct pvt_sensor_info pvt_info[] = {
> * 48380,
> * where T = [-48380, 147438] mC and N = [0, 1023].
> */
> +#if defined(CONFIG_SENSORS_BT1_PVT_ALARMS)
> static const struct pvt_poly poly_temp_to_N = {
> .total_divider = 10000,
> .terms = {
> @@ -74,6 +75,7 @@ static const struct pvt_poly poly_temp_to_N = {
> {0, 1720400, 1, 1}
> }
> };
> +#endif /* CONFIG_SENSORS_BT1_PVT_ALARMS */
>
> static const struct pvt_poly poly_N_to_temp = {
> .total_divider = 1,
> @@ -96,6 +98,7 @@ static const struct pvt_poly poly_N_to_temp = {
> * N = (18658e-3*V - 11572) / 10,
> * V = N * 10^5 / 18658 + 11572 * 10^4 / 18658.
> */
> +#if defined(CONFIG_SENSORS_BT1_PVT_ALARMS)
> static const struct pvt_poly poly_volt_to_N = {
> .total_divider = 10,
> .terms = {
> @@ -103,6 +106,7 @@ static const struct pvt_poly poly_volt_to_N = {
> {0, -11572, 1, 1}
> }
> };
> +#endif /* CONFIG_SENSORS_BT1_PVT_ALARMS */
>
> static const struct pvt_poly poly_N_to_volt = {
> .total_divider = 10,
next prev parent reply other threads:[~2020-06-02 14:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 9:12 [PATCH] hwmon: bt1-pvt: Declare Temp- and Volt-to-N poly when alarms are enabled Serge Semin
2020-06-02 14:07 ` Guenter Roeck [this message]
2020-06-02 23:33 ` Serge Semin
2020-06-03 0:07 ` [PATCH v2] hwmon: bt1-pvt: Define Temp- and Volt-to-N poly as maybe-unused Serge Semin
2020-06-04 15:30 ` Guenter Roeck
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