Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
On Fri, Dec 11, 2020 at 10:28:35AM +0100, Lino Sanfilippo wrote: > Hi Uwe, > > > Gesendet: Donnerstag, 10. Dezember 2020 um 12:43 Uhr > > Von: "Uwe Kleine-König" > > An: "Lino Sanfilippo" > > Cc: thierry.red...@gmail.com, lee.jo...@linaro.org, nsaenzjulie...@suse.de, > > f.faine...@gmail.com, r...@broadcom.com, s...@mess.org, > > sbran...@broadcom.com, bcm-kernel-feedback-l...@broadcom.com, > > linux-...@vger.kernel.org, linux-rpi-ker...@lists.infradead.org, > > linux-arm-ker...@lists.infradead.org, linux-kernel@vger.kernel.org > > Betreff: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic > > configuration > > > > > Side note: I'm a bit surprised about the output of > > > > b4 diff 1607464905-16630-1-git-send-email-linosanfili...@gmx.de > > > > This is probably due to the fact that compared to v3 you also rebased. > > Still the diff is quite big. > > You are right, I made a rebase before I created the last patch, sorry for the > confusion this caused. > Anyway, thanks for the review(s)! You did everything good enough. (To further improve, you could use git-format-patch's --base option and mention a rebase in the series' changelog; note this is quite high level critic.) This was more me wondering the output is not easier to use. (And note I also showed the wrong commandline, but that doesn't resolve the issue. The right command is: b4 diff 1607546905-20549-1-git-send-email-linosanfili...@gmx.de .) Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König| Industrial Linux Solutions | https://www.pengutronix.de/ | signature.asc Description: PGP signature
Aw: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
Hi Uwe, > Gesendet: Donnerstag, 10. Dezember 2020 um 12:43 Uhr > Von: "Uwe Kleine-König" > An: "Lino Sanfilippo" > Cc: thierry.red...@gmail.com, lee.jo...@linaro.org, nsaenzjulie...@suse.de, > f.faine...@gmail.com, r...@broadcom.com, s...@mess.org, > sbran...@broadcom.com, bcm-kernel-feedback-l...@broadcom.com, > linux-...@vger.kernel.org, linux-rpi-ker...@lists.infradead.org, > linux-arm-ker...@lists.infradead.org, linux-kernel@vger.kernel.org > Betreff: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic > configuration > > Side note: I'm a bit surprised about the output of > > b4 diff 1607464905-16630-1-git-send-email-linosanfili...@gmx.de > > This is probably due to the fact that compared to v3 you also rebased. > Still the diff is quite big. You are right, I made a rebase before I created the last patch, sorry for the confusion this caused. Anyway, thanks for the review(s)! Regards, Lino
Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
Hello, On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote: > Use the newer .apply function of pwm_ops instead of .config, .enable, > .disable and .set_polarity. This guarantees atomic changes of the pwm > controller configuration. It also reduces the size of the driver. > > Since now period is a 64 bit value, add an extra check to reject periods > that exceed the possible max value for the 32 bit register. > > This has been tested on a Raspberry PI 4. > > Signed-off-by: Lino Sanfilippo Reviewed-by: Uwe Kleine-König Side note: I'm a bit surprised about the output of b4 diff 1607464905-16630-1-git-send-email-linosanfili...@gmx.de This is probably due to the fact that compared to v3 you also rebased. Still the diff is quite big. Best regards and thanks for your patch Uwe -- Pengutronix e.K. | Uwe Kleine-König| Industrial Linux Solutions | https://www.pengutronix.de/ | signature.asc Description: PGP signature
Aw: Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
Hi Uwe
> Hello Lino,
>
> On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> > Use the newer .apply function of pwm_ops instead of .config, .enable,
> > .disable and .set_polarity. This guarantees atomic changes of the pwm
> > controller configuration. It also reduces the size of the driver.
> >
> > Since now period is a 64 bit value, add an extra check to reject periods
> > that exceed the possible max value for the 32 bit register.
> >
> > This has been tested on a Raspberry PI 4.
>
> This looks right, just two small nitpicks below.
>
>
> This cast isn't necessary. (And if it was, I *think* the space between
> "(u32)" and "period" is wrong. But my expectation that checkpatch warns
> about this is wrong, so take this with a grain of salt.)
OK, I will omit the cast in the next patch version (it was primarily
meant for documentation purposes but now it seems to me rather
unusual for kernel code)
>
> > - value = readl(pc->base + PWM_CONTROL);
> > - value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > - writel(value, pc->base + PWM_CONTROL);
> > -}
> > + /* set duty cycle */
> > + val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
> > + writel(val, pc->base + DUTY(pwm->hwpwm));
> >
> > -static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device
> > *pwm,
> > - enum pwm_polarity polarity)
> > -{
> > - struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> > - u32 value;
> > + /* set polarity */
> > + val = readl(pc->base + PWM_CONTROL);
> >
> > - value = readl(pc->base + PWM_CONTROL);
> > + if (state->polarity == PWM_POLARITY_NORMAL)
> > + val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > + else
> > + val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> >
> > - if (polarity == PWM_POLARITY_NORMAL)
> > - value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> > + /* enable/disable */
> > + if (state->enabled)
> > + val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> > else
> > - value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> > + val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> >
> > - writel(value, pc->base + PWM_CONTROL);
> > + writel(val, pc->base + PWM_CONTROL);
> >
> > return 0;
> > }
> >
> > +
>
> I wouldn't have added this empty line. But I guess that's subjective. Or
> did you add this by mistake?
I cannot remember that the line was added by intention, so I am fine to remove
it.
Thanks and regards,
Lino
Re: [PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
Hello Lino,
On Tue, Dec 08, 2020 at 11:01:45PM +0100, Lino Sanfilippo wrote:
> Use the newer .apply function of pwm_ops instead of .config, .enable,
> .disable and .set_polarity. This guarantees atomic changes of the pwm
> controller configuration. It also reduces the size of the driver.
>
> Since now period is a 64 bit value, add an extra check to reject periods
> that exceed the possible max value for the 32 bit register.
>
> This has been tested on a Raspberry PI 4.
This looks right, just two small nitpicks below.
> Signed-off-by: Lino Sanfilippo
> ---
>
> v3: Check against period truncation (based on a review by Uwe Kleine-König)
> v2: Fix compiler error for 64 bit builds
>
> drivers/pwm/pwm-bcm2835.c | 72
> +--
> 1 file changed, 26 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
> index 6841dcf..d339898 100644
> --- a/drivers/pwm/pwm-bcm2835.c
> +++ b/drivers/pwm/pwm-bcm2835.c
> @@ -58,13 +58,15 @@ static void bcm2835_pwm_free(struct pwm_chip *chip,
> struct pwm_device *pwm)
> writel(value, pc->base + PWM_CONTROL);
> }
>
> -static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> - int duty_ns, int period_ns)
> +static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> {
> +
> struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> unsigned long rate = clk_get_rate(pc->clk);
> + unsigned long long period;
> unsigned long scaler;
> - u32 period;
> + u32 val;
>
> if (!rate) {
> dev_err(pc->dev, "failed to get clock rate\n");
> @@ -72,65 +74,43 @@ static int bcm2835_pwm_config(struct pwm_chip *chip,
> struct pwm_device *pwm,
> }
>
> scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
> - period = DIV_ROUND_CLOSEST(period_ns, scaler);
> + /* set period */
> + period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
>
> - if (period < PERIOD_MIN)
> + /* dont accept a period that is too small or has been truncated */
> + if ((period < PERIOD_MIN) || (period > U32_MAX))
> return -EINVAL;
>
> - writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
> -pc->base + DUTY(pwm->hwpwm));
> - writel(period, pc->base + PERIOD(pwm->hwpwm));
> -
> - return 0;
> -}
> -
> -static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> -{
> - struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> - u32 value;
> -
> - value = readl(pc->base + PWM_CONTROL);
> - value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> - writel(value, pc->base + PWM_CONTROL);
> -
> - return 0;
> -}
> -
> -static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device
> *pwm)
> -{
> - struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> - u32 value;
> + writel((u32) period, pc->base + PERIOD(pwm->hwpwm));
This cast isn't necessary. (And if it was, I *think* the space between
"(u32)" and "period" is wrong. But my expectation that checkpatch warns
about this is wrong, so take this with a grain of salt.)
> - value = readl(pc->base + PWM_CONTROL);
> - value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
> - writel(value, pc->base + PWM_CONTROL);
> -}
> + /* set duty cycle */
> + val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
> + writel(val, pc->base + DUTY(pwm->hwpwm));
>
> -static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device
> *pwm,
> - enum pwm_polarity polarity)
> -{
> - struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> - u32 value;
> + /* set polarity */
> + val = readl(pc->base + PWM_CONTROL);
>
> - value = readl(pc->base + PWM_CONTROL);
> + if (state->polarity == PWM_POLARITY_NORMAL)
> + val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> + else
> + val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
>
> - if (polarity == PWM_POLARITY_NORMAL)
> - value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
> + /* enable/disable */
> + if (state->enabled)
> + val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
> else
> - value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
> + val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
>
> - writel(value, pc->base + PWM_CONTROL);
> + writel(val, pc->base + PWM_CONTROL);
>
> return 0;
> }
>
> +
I wouldn't have added this empty line. But I guess that's subjective. Or
did you add this by mistake?
> static const struct pwm_ops bcm2835_pwm_ops = {
> .request = bcm2835_pwm_request,
> .free = bcm2835_pwm_free,
> - .config = bcm2835_pwm_config,
> - .enable = bcm2835_pwm_enable,
> - .disable = bcm2835_pwm_disable,
> - .set_polarity = bcm
[PATCH v3] pwm: bcm2835: Support apply function for atomic configuration
Use the newer .apply function of pwm_ops instead of .config, .enable,
.disable and .set_polarity. This guarantees atomic changes of the pwm
controller configuration. It also reduces the size of the driver.
Since now period is a 64 bit value, add an extra check to reject periods
that exceed the possible max value for the 32 bit register.
This has been tested on a Raspberry PI 4.
Signed-off-by: Lino Sanfilippo
---
v3: Check against period truncation (based on a review by Uwe Kleine-König)
v2: Fix compiler error for 64 bit builds
drivers/pwm/pwm-bcm2835.c | 72 +--
1 file changed, 26 insertions(+), 46 deletions(-)
diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
index 6841dcf..d339898 100644
--- a/drivers/pwm/pwm-bcm2835.c
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -58,13 +58,15 @@ static void bcm2835_pwm_free(struct pwm_chip *chip, struct
pwm_device *pwm)
writel(value, pc->base + PWM_CONTROL);
}
-static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
- int duty_ns, int period_ns)
+static int bcm2835_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+const struct pwm_state *state)
{
+
struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
unsigned long rate = clk_get_rate(pc->clk);
+ unsigned long long period;
unsigned long scaler;
- u32 period;
+ u32 val;
if (!rate) {
dev_err(pc->dev, "failed to get clock rate\n");
@@ -72,65 +74,43 @@ static int bcm2835_pwm_config(struct pwm_chip *chip, struct
pwm_device *pwm,
}
scaler = DIV_ROUND_CLOSEST(NSEC_PER_SEC, rate);
- period = DIV_ROUND_CLOSEST(period_ns, scaler);
+ /* set period */
+ period = DIV_ROUND_CLOSEST_ULL(state->period, scaler);
- if (period < PERIOD_MIN)
+ /* dont accept a period that is too small or has been truncated */
+ if ((period < PERIOD_MIN) || (period > U32_MAX))
return -EINVAL;
- writel(DIV_ROUND_CLOSEST(duty_ns, scaler),
- pc->base + DUTY(pwm->hwpwm));
- writel(period, pc->base + PERIOD(pwm->hwpwm));
-
- return 0;
-}
-
-static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
- u32 value;
-
- value = readl(pc->base + PWM_CONTROL);
- value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
- writel(value, pc->base + PWM_CONTROL);
-
- return 0;
-}
-
-static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
- u32 value;
+ writel((u32) period, pc->base + PERIOD(pwm->hwpwm));
- value = readl(pc->base + PWM_CONTROL);
- value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
- writel(value, pc->base + PWM_CONTROL);
-}
+ /* set duty cycle */
+ val = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, scaler);
+ writel(val, pc->base + DUTY(pwm->hwpwm));
-static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
- enum pwm_polarity polarity)
-{
- struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
- u32 value;
+ /* set polarity */
+ val = readl(pc->base + PWM_CONTROL);
- value = readl(pc->base + PWM_CONTROL);
+ if (state->polarity == PWM_POLARITY_NORMAL)
+ val &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
+ else
+ val |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
- if (polarity == PWM_POLARITY_NORMAL)
- value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
+ /* enable/disable */
+ if (state->enabled)
+ val |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
else
- value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
+ val &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
- writel(value, pc->base + PWM_CONTROL);
+ writel(val, pc->base + PWM_CONTROL);
return 0;
}
+
static const struct pwm_ops bcm2835_pwm_ops = {
.request = bcm2835_pwm_request,
.free = bcm2835_pwm_free,
- .config = bcm2835_pwm_config,
- .enable = bcm2835_pwm_enable,
- .disable = bcm2835_pwm_disable,
- .set_polarity = bcm2835_set_polarity,
+ .apply = bcm2835_pwm_apply,
.owner = THIS_MODULE,
};
--
2.7.4
