[PATCH v2 0/2] meson pwm small fixes

[PATCH v2 0/2] meson pwm small fixes

[George Stark]

Just some small fixes for meson pwm.

Changelog:
v1->v2:
  pwm: meson: Drop unneeded check in .get_state()
    - update commit message
    - drop Fixes tag. It's not actually a bug
    previous version: [1]

  pwm: meson: Add check for error from clk_round_rate()
    - update commit message
    - change unsigned long fin_freq; to long fin_freq;
    previous version: [2]

[1] https://lore.kernel.org/lkml/20240423161356.2522636-2-gnstark@salutedevices.com/T/#m6d1d5cf100dc5b77f85e2a7d01c0b0097b6a04da
[2] https://lore.kernel.org/lkml/20240423161356.2522636-2-gnstark@salutedevices.com/T/#ma84e2d490bf79bda12f8393773c1af37b48d5473

George Stark (2):
  pwm: meson: Drop unneeded check in .get_state()
  pwm: meson: Add check for error from clk_round_rate()

 drivers/pwm/pwm-meson.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--
2.25.1


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[PATCH v2 1/2] pwm: meson: Drop unneeded check in .get_state()

[George Stark]

Drop checking state argument for NULL pointer in meson_pwm_get_state()
due to it is called only from pwm core with always valid arguments.

Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
Signed-off-by: George Stark <gnstark@salutedevices.com>
---
 drivers/pwm/pwm-meson.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index ea96c5973488..f4d70da621ec 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -311,9 +311,6 @@ static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	struct meson_pwm_channel *channel;
 	u32 value;

-	if (!state)
-		return 0;
-
 	channel = &meson->channels[pwm->hwpwm];
 	channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];

--
2.25.1


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[PATCH v2 2/2] pwm: meson: Add check for error from clk_round_rate()

[George Stark]

clk_round_rate() can return not only zero if requested frequency can not
be provided but also negative error code so add check for it too.

Also change type of variable holding clk_round_rate() result from
unsigned long to long. It's safe due to clk_round_rate() returns long.

Fixes: 329db102a26d ("pwm: meson: make full use of common clock framework")
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
Signed-off-by: George Stark <gnstark@salutedevices.com>
---
 drivers/pwm/pwm-meson.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index f4d70da621ec..d4228ac1e7ea 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -148,7 +148,7 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm,
 	struct meson_pwm *meson = to_meson_pwm(chip);
 	struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
 	unsigned int cnt, duty_cnt;
-	unsigned long fin_freq;
+	long fin_freq;
 	u64 duty, period, freq;
 
 	duty = state->duty_cycle;
@@ -168,9 +168,10 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm,
 		freq = ULONG_MAX;
 
 	fin_freq = clk_round_rate(channel->clk, freq);
-	if (fin_freq == 0) {
-		dev_err(pwmchip_parent(chip), "invalid source clock frequency\n");
-		return -EINVAL;
+	if (fin_freq <= 0) {
+		dev_err(pwmchip_parent(chip),
+			"invalid source clock frequency %llu\n", freq);
+		return fin_freq ? fin_freq : -EINVAL;
 	}
 
 	dev_dbg(pwmchip_parent(chip), "fin_freq: %lu Hz\n", fin_freq);
-- 
2.25.1


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Re: [PATCH v2 2/2] pwm: meson: Add check for error from clk_round_rate()

[Uwe Kleine-König]

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On Wed, Apr 24, 2024 at 04:24:08PM +0300, George Stark wrote:
> clk_round_rate() can return not only zero if requested frequency can not
> be provided but also negative error code so add check for it too.
> 
> Also change type of variable holding clk_round_rate() result from
> unsigned long to long. It's safe due to clk_round_rate() returns long.
> 
> Fixes: 329db102a26d ("pwm: meson: make full use of common clock framework")
> Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
> Signed-off-by: George Stark <gnstark@salutedevices.com>
> ---
>  drivers/pwm/pwm-meson.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index f4d70da621ec..d4228ac1e7ea 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -148,7 +148,7 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm,
>  	struct meson_pwm *meson = to_meson_pwm(chip);
>  	struct meson_pwm_channel *channel = &meson->channels[pwm->hwpwm];
>  	unsigned int cnt, duty_cnt;
> -	unsigned long fin_freq;
> +	long fin_freq;
>  	u64 duty, period, freq;
>  
>  	duty = state->duty_cycle;
> @@ -168,9 +168,10 @@ static int meson_pwm_calc(struct pwm_chip *chip, struct pwm_device *pwm,
>  		freq = ULONG_MAX;
>  
>  	fin_freq = clk_round_rate(channel->clk, freq);
> -	if (fin_freq == 0) {
> -		dev_err(pwmchip_parent(chip), "invalid source clock frequency\n");
> -		return -EINVAL;
> +	if (fin_freq <= 0) {
> +		dev_err(pwmchip_parent(chip),
> +			"invalid source clock frequency %llu\n", freq);
> +		return fin_freq ? fin_freq : -EINVAL;
>  	}
>  
>  	dev_dbg(pwmchip_parent(chip), "fin_freq: %lu Hz\n", fin_freq);
                                                   ^
With fin_freq now being unsigned, this ------------' should be a 'd'.

If you want to still extend your fixes series: A bit further below there
is

	cnt = div_u64(fin_freq * period, NSEC_PER_SEC);

. The multiplication there might overflow. This should better use
mul_u64_u64_div_u64() (or one of it's variants).

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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