Hi, Am Freitag, 13. Oktober 2023, 13:04:48 CEST schrieb Stefan Wahren: > Hi Sean, > > Am 13.10.23 um 12:46 schrieb Sean Young: > > clk_get_rate() may do a mutex lock. Since the clock rate cannot change on > > an rpi, simply fetch it once. > > does it mean you checked all possible SoCs (BCM2835, BCM2836, BCM2837, > BCM2711, BCM2712) for this change? > > Is it impossible that the real clock can never be influenced by turbo > mode like SPI? Assuming the clock can change, which I would, then a clock notifier seems appropriate. See [1] for an example. Best regards, Alexander [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ commit/?id=90ad2cbe88c22d0215225ab9594eeead0eb24fde > Best regards > > > Signed-off-by: Sean Young <sean@xxxxxxxx> > > --- > > > > drivers/pwm/pwm-bcm2835.c | 21 ++++++++++++--------- > > 1 file changed, 12 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c > > index bdfc2a5ec0d6..59ea154dd657 100644 > > --- a/drivers/pwm/pwm-bcm2835.c > > +++ b/drivers/pwm/pwm-bcm2835.c > > @@ -28,6 +28,7 @@ struct bcm2835_pwm { > > > > struct device *dev; > > void __iomem *base; > > struct clk *clk; > > > > + unsigned long rate; > > > > }; > > > > static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip) > > > > @@ -63,17 +64,11 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, > > struct pwm_device *pwm,> > > { > > > > struct bcm2835_pwm *pc = to_bcm2835_pwm(chip); > > > > - unsigned long rate = clk_get_rate(pc->clk); > > > > unsigned long long period_cycles; > > u64 max_period; > > > > u32 val; > > > > - if (!rate) { > > - dev_err(pc->dev, "failed to get clock rate\n"); > > - return -EINVAL; > > - } > > - > > > > /* > > > > * period_cycles must be a 32 bit value, so period * rate / > > NSEC_PER_SEC > > * must be <= U32_MAX. As U32_MAX * NSEC_PER_SEC < U64_MAX the > > > > @@ -88,13 +83,13 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, > > struct pwm_device *pwm,> > > * <=> period < ((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate > > * <=> period <= ceil((U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC/2) / rate) > > - 1 > > */ > > > > - max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * NSEC_PER_SEC + NSEC_PER_SEC > > / 2, rate) - 1; + max_period = DIV_ROUND_UP_ULL((u64)U32_MAX * > > NSEC_PER_SEC + NSEC_PER_SEC / 2, pc->rate) - 1;> > > if (state->period > max_period) > > > > return -EINVAL; > > > > /* set period */ > > > > - period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * rate, > > NSEC_PER_SEC); + period_cycles = DIV_ROUND_CLOSEST_ULL(state->period * > > pc->rate, NSEC_PER_SEC);> > > /* don't accept a period that is too small */ > > if (period_cycles < PERIOD_MIN) > > > > @@ -103,7 +98,7 @@ static int bcm2835_pwm_apply(struct pwm_chip *chip, > > struct pwm_device *pwm,> > > writel(period_cycles, pc->base + PERIOD(pwm->hwpwm)); > > > > /* set duty cycle */ > > > > - val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * rate, NSEC_PER_SEC); > > + val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle * pc->rate, NSEC_PER_SEC); > > > > writel(val, pc->base + DUTY(pwm->hwpwm)); > > > > /* set polarity */ > > > > @@ -129,6 +124,7 @@ static const struct pwm_ops bcm2835_pwm_ops = { > > > > .request = bcm2835_pwm_request, > > .free = bcm2835_pwm_free, > > .apply = bcm2835_pwm_apply, > > > > + .atomic = true, > > > > .owner = THIS_MODULE, > > > > }; > > > > @@ -156,6 +152,13 @@ static int bcm2835_pwm_probe(struct platform_device > > *pdev)> > > if (ret) > > > > return ret; > > > > + pc->rate = clk_get_rate(pc->clk); > > + if (!pc->rate) { > > + dev_err(pc->dev, "failed to get clock rate\n"); > > + ret = -EINVAL; > > + goto add_fail; > > + } > > + > > > > pc->chip.dev = &pdev->dev; > > pc->chip.ops = &bcm2835_pwm_ops; > > pc->chip.npwm = 2; -- TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht München, HRB 105018 Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider http://www.tq-group.com/
