On Sat, 11 Oct 2014, Vladimir Zapolskiy wrote:
> If PWM device is requested by means of legacy API pwm_request(), its
> resources are not freed on module unbind, which may cause an oops on
> access, e.g. by reading /sys/kernel/debug/pwm.
>
> Reported-by: Dmitry Eremin-Solenikov <dmitry_eremin@xxxxxxxxxx>
> Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@xxxxxxxxxx>
> ---
> drivers/video/backlight/pwm_bl.c | 4 ++++
> 1 file changed, 4 insertions(+)
Applied with Thierry's Ack.
> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> index dd7aaf7..40770dd 100644
> --- a/drivers/video/backlight/pwm_bl.c
> +++ b/drivers/video/backlight/pwm_bl.c
> @@ -34,6 +34,7 @@ struct pwm_bl_data {
> struct regulator *power_supply;
> struct gpio_desc *enable_gpio;
> unsigned int scale;
> + bool legacy;
> int (*notify)(struct device *,
> int brightness);
> void (*notify_after)(struct device *,
> @@ -274,6 +275,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
> pb->pwm = devm_pwm_get(&pdev->dev, NULL);
> if (IS_ERR(pb->pwm) && !pdev->dev.of_node) {
> dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
> + pb->legacy = true;
> pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
> }
>
> @@ -339,6 +341,8 @@ static int pwm_backlight_remove(struct platform_device *pdev)
>
> if (pb->exit)
> pb->exit(&pdev->dev);
> + if (pb->legacy)
> + pwm_free(pb->pwm);
>
> return 0;
> }
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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