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(+)
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;
}
--
1.7.10.4
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