On Thu, Sep 23, 2021 at 11:34:47AM +0900, Akinobu Mita wrote:
> This adds an optional property "retain-state-shutdown" as requested by
> Billy Tsai.
>
> Billy said:
> "Our platform is BMC that will use a PWM-FAN driver to control the fan
> on the managed host. In our case, we do not want to stop the fan when
> the BMC is reboot, which may cause the temperature of the managed host
> not to be lowered."
>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>
> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
For my reference (waiting for DT property approval):
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Guenter
> ---
> drivers/hwmon/pwm-fan.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 17518b4cab1b..1ea0d0562c28 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -38,6 +38,7 @@ struct pwm_fan_ctx {
> struct pwm_fan_tach *tachs;
> ktime_t sample_start;
> struct timer_list rpm_timer;
> + bool retain_state_shutdown;
>
> unsigned int pwm_value;
> unsigned int pwm_fan_state;
> @@ -312,6 +313,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
>
> mutex_init(&ctx->lock);
>
> + ctx->retain_state_shutdown =
> + of_property_read_bool(dev->of_node, "retain-state-shutdown");
> +
> ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
> if (IS_ERR(ctx->pwm))
> return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not get PWM\n");
> @@ -492,7 +496,10 @@ static int pwm_fan_disable(struct device *dev)
>
> static void pwm_fan_shutdown(struct platform_device *pdev)
> {
> - pwm_fan_disable(&pdev->dev);
> + struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
> +
> + if (!ctx->retain_state_shutdown)
> + pwm_fan_disable(&pdev->dev);
> }
>
> #ifdef CONFIG_PM_SLEEP
