6.1-stable review patch. If anyone has any objections, please let me know.
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From: Uwe Kleine-König u.kleine-koenig@baylibre.com
[ Upstream commit 37f7707077f5ea2515bf4b1dc7fad43f8e12993e ]
The hardware only supports a single period length for both PWM outputs. So atmel_tcb_pwm_config() checks the configuration of the other output if it's compatible with the currently requested setting. The register values are then actually updated in atmel_tcb_pwm_enable(). To make this race free the lock must be held during the whole process, so grab the lock in .apply() instead of individually in atmel_tcb_pwm_disable() and atmel_tcb_pwm_enable() which then also covers atmel_tcb_pwm_config().
To simplify handling, use the guard helper to let the compiler care for unlocking. Otherwise unlocking would be more difficult as there is more than one exit path in atmel_tcb_pwm_apply().
Fixes: 9421bade0765 ("pwm: atmel: add Timer Counter Block PWM driver") Signed-off-by: Uwe Kleine-König u.kleine-koenig@baylibre.com Acked-by: Nicolas Ferre nicolas.ferre@microchip.com Link: https://lore.kernel.org/r/20240709101806.52394-3-u.kleine-koenig@baylibre.co... Signed-off-by: Uwe Kleine-König ukleinek@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pwm/pwm-atmel-tcb.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/drivers/pwm/pwm-atmel-tcb.c b/drivers/pwm/pwm-atmel-tcb.c index 30c966238e41c..e74b45f00a9ac 100644 --- a/drivers/pwm/pwm-atmel-tcb.c +++ b/drivers/pwm/pwm-atmel-tcb.c @@ -83,7 +83,8 @@ static int atmel_tcb_pwm_request(struct pwm_chip *chip, tcbpwm->period = 0; tcbpwm->div = 0;
- spin_lock(&tcbpwmc->lock); + guard(spinlock)(&tcbpwmc->lock); + regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr); /* * Get init config from Timer Counter registers if @@ -109,7 +110,6 @@ static int atmel_tcb_pwm_request(struct pwm_chip *chip,
cmr |= ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO | ATMEL_TC_EEVT_XC0; regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), cmr); - spin_unlock(&tcbpwmc->lock);
return 0; } @@ -139,7 +139,6 @@ static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm, if (tcbpwm->duty == 0) polarity = !polarity;
- spin_lock(&tcbpwmc->lock); regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr);
/* flush old setting and set the new one */ @@ -174,8 +173,6 @@ static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm, ATMEL_TC_SWTRG); tcbpwmc->bkup.enabled = 0; } - - spin_unlock(&tcbpwmc->lock); }
static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, @@ -196,7 +193,6 @@ static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, if (tcbpwm->duty == 0) polarity = !polarity;
- spin_lock(&tcbpwmc->lock); regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr);
/* flush old setting and set the new one */ @@ -258,7 +254,6 @@ static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CCR), ATMEL_TC_SWTRG | ATMEL_TC_CLKEN); tcbpwmc->bkup.enabled = 1; - spin_unlock(&tcbpwmc->lock); return 0; }
@@ -343,9 +338,12 @@ static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, static int atmel_tcb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { + struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip); int duty_cycle, period; int ret;
+ guard(spinlock)(&tcbpwmc->lock); + if (!state->enabled) { atmel_tcb_pwm_disable(chip, pwm, state->polarity); return 0;