From 4eb67a209645a87b8aca070aa9735eed90177829 Mon Sep 17 00:00:00 2001 From: Fabrice Gasnier Date: Wed, 14 Feb 2018 11:04:33 +0100 Subject: [PATCH] pwm: stm32: Protect common prescaler for all channels There may be a race, when configuring two PWM channels, with different prescaler values, when there's no active channel yet. Add mutex lock to avoid concurrent access on PWM apply state. This is also precursor patch for PWM capture support. Signed-off-by: Fabrice Gasnier Reviewed-by: Benjamin Gaignard Signed-off-by: Thierry Reding --- drivers/pwm/pwm-stm32.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c index 014e2a759fa6..2708212933f7 100644 --- a/drivers/pwm/pwm-stm32.c +++ b/drivers/pwm/pwm-stm32.c @@ -20,6 +20,7 @@ struct stm32_pwm { struct pwm_chip chip; + struct mutex lock; /* protect pwm config/enable */ struct clk *clk; struct regmap *regmap; u32 max_arr; @@ -212,9 +213,23 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, return ret; } +static int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct stm32_pwm *priv = to_stm32_pwm_dev(chip); + int ret; + + /* protect common prescaler for all active channels */ + mutex_lock(&priv->lock); + ret = stm32_pwm_apply(chip, pwm, state); + mutex_unlock(&priv->lock); + + return ret; +} + static const struct pwm_ops stm32pwm_ops = { .owner = THIS_MODULE, - .apply = stm32_pwm_apply, + .apply = stm32_pwm_apply_locked, }; static int stm32_pwm_set_breakinput(struct stm32_pwm *priv, @@ -334,6 +349,7 @@ static int stm32_pwm_probe(struct platform_device *pdev) if (!priv) return -ENOMEM; + mutex_init(&priv->lock); priv->regmap = ddata->regmap; priv->clk = ddata->clk; priv->max_arr = ddata->max_arr; -- 2.25.1