[PATCH v3] pwm: meson: modify and simplify calculation in meson_pwm_get_state

[PATCH v3] pwm: meson: modify and simplify calculation in meson_pwm_get_state

[Heiner Kallweit]

I don't see a reason why we should treat the case lo < hi differently
and return 0 as period and duty_cycle. The current logic was added with
c375bcbaabdb ("pwm: meson: Read the full hardware state in
meson_pwm_get_state()"), Martin as original author doesn't remember why
it was implemented this way back then.
So let's handle it as normal use case and also remove the optimization
for lo == 0. I think the improved readability is worth it.

Fixes: c375bcbaabdb ("pwm: meson: Read the full hardware state in meson_pwm_get_state()")
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- improve commit description
v3:
- make patch a fix
---
 drivers/pwm/pwm-meson.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 5732300eb..3865538dd 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -351,18 +351,8 @@ static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	channel->lo = FIELD_GET(PWM_LOW_MASK, value);
 	channel->hi = FIELD_GET(PWM_HIGH_MASK, value);
 
-	if (channel->lo == 0) {
-		state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
-		state->duty_cycle = state->period;
-	} else if (channel->lo >= channel->hi) {
-		state->period = meson_pwm_cnt_to_ns(chip, pwm,
-						    channel->lo + channel->hi);
-		state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm,
-							channel->hi);
-	} else {
-		state->period = 0;
-		state->duty_cycle = 0;
-	}
+	state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->lo + channel->hi);
+	state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
 
 	state->polarity = PWM_POLARITY_NORMAL;
 
-- 
2.40.0

Re: [PATCH v3] pwm: meson: modify and simplify calculation in meson_pwm_get_state

[Martin Blumenstingl]

On Tue, May 2, 2023 at 10:33 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>
> I don't see a reason why we should treat the case lo < hi differently
> and return 0 as period and duty_cycle. The current logic was added with
> c375bcbaabdb ("pwm: meson: Read the full hardware state in
> meson_pwm_get_state()"), Martin as original author doesn't remember why
> it was implemented this way back then.
> So let's handle it as normal use case and also remove the optimization
> for lo == 0. I think the improved readability is worth it.
>
> Fixes: c375bcbaabdb ("pwm: meson: Read the full hardware state in meson_pwm_get_state()")
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Cc: stable@vger.kernel.org
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Re: [PATCH v3] pwm: meson: modify and simplify calculation in meson_pwm_get_state

[Dmitry Rokosov]

On Tue, May 02, 2023 at 10:33:42PM +0200, Heiner Kallweit wrote:
> I don't see a reason why we should treat the case lo < hi differently
> and return 0 as period and duty_cycle. The current logic was added with
> c375bcbaabdb ("pwm: meson: Read the full hardware state in
> meson_pwm_get_state()"), Martin as original author doesn't remember why
> it was implemented this way back then.
> So let's handle it as normal use case and also remove the optimization
> for lo == 0. I think the improved readability is worth it.
> 
> Fixes: c375bcbaabdb ("pwm: meson: Read the full hardware state in meson_pwm_get_state()")
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Cc: stable@vger.kernel.org
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> v2:
> - improve commit description
> v3:
> - make patch a fix
> ---
>  drivers/pwm/pwm-meson.c | 14 ++------------
>  1 file changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index 5732300eb..3865538dd 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -351,18 +351,8 @@ static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  	channel->lo = FIELD_GET(PWM_LOW_MASK, value);
>  	channel->hi = FIELD_GET(PWM_HIGH_MASK, value);
>  
> -	if (channel->lo == 0) {
> -		state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
> -		state->duty_cycle = state->period;
> -	} else if (channel->lo >= channel->hi) {
> -		state->period = meson_pwm_cnt_to_ns(chip, pwm,
> -						    channel->lo + channel->hi);
> -		state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm,
> -							channel->hi);
> -	} else {
> -		state->period = 0;
> -		state->duty_cycle = 0;
> -	}
> +	state->period = meson_pwm_cnt_to_ns(chip, pwm, channel->lo + channel->hi);
> +	state->duty_cycle = meson_pwm_cnt_to_ns(chip, pwm, channel->hi);
>  
>  	state->polarity = PWM_POLARITY_NORMAL;
>  
> -- 
> 2.40.0

Reviewed-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>

-- 
Thank you,
Dmitry