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Convert PWM period and duty cycle to u64

PATCH Superseded Guru Das Srinagesh 4 participants 21 messages Mar 17, 2020 – Mar 19, 2020

Subsystems (15)

v9 of 16 Superseded Latest is v16 →

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#0 lore raw

v9 cover Convert PWM period and duty cycle to u64

Because period and duty cycle are defined in the PWM framework structs as ints with units of nanoseconds, the maximum time duration that can be set is limited to ~2.147 seconds. Consequently, applications desiring to set greater time periods via the PWM framework are not be able to do so - like, for instance, causing an LED to blink at an interval of 5 seconds.

Redefining the period and duty cycle struct members in the core PWM framework structs as u64 values will enable larger time durations to be set and solve this problem. Such a change to the framework mandates that drivers using these struct members (and corresponding helper functions) also be modified correctly in order to prevent compilation errors.

This patch series introduces the changes to all the drivers first, followed by the framework change at the very end so that when the latter is applied, all the drivers are in good shape and there are no compilation errors.

Changes from v8:
- Gathered all received "Acked-by: " and "Reviewed-by: " tags
- Dropped patch to clk-pwm.c for reasons mentiond in [2]
- Expanded audience of unreviewed patches

Changes from v7:
- Changed commit messages of all patches to be brief and to the point.
- Added explanation of change in cover letter.
- Dropped change to pwm-sti.c as upon review it was unnecessary as struct pwm_capture is not being modified in the PWM core.

Changes from v6:
- Split out the driver changes out into separate patches, one patch per file for ease of reviewing.

Changes from v5:
- Dropped the conversion of struct pwm_capture to u64 for reasons mentioned

    in https://www.spinics.net/lists/linux-pwm/msg11541.html

Changes from v4:
- Split the patch into two: one for changes to the drivers, and the actual switch to u64 for ease of reverting should the need arise.
- Re-examined the patch and made the following corrections:
* intel_panel.c:
DIV64_U64_ROUND_UP -> DIV_ROUND_UP_ULL (as only the numerator would be 64-bit in this case).
* pwm-sti.c:
do_div -> div_u64 (do_div is optimized only for x86 architectures, and div_u64's comment block suggests to use this as much as possible).

Changes from v3:
- Rebased to current tip of for-next.

Changes from v2:
- Fixed %u -> %llu in a dev_dbg in pwm-stm32-lp.c, thanks to kbuild test robot
- Added a couple of fixes to pwm-imx-tpm.c and pwm-sifive.c

Changes from v1:
- Fixed compilation errors seen when compiling for different archs.

v1:
- Reworked the change pushed upstream earlier [1] so as to not add an extension to an obsolete API. With this change, pwm_ops->apply() can be used to set pwm_state parameters as usual.

[1] https://lore.kernel.org/lkml/20190916140048.GB7488@ulmo/
[2] https://lore.kernel.org/lkml/[email protected]/

Guru Das Srinagesh (11):
drm/i915: Use 64-bit division macro
hwmon: pwm-fan: Use 64-bit division macro
ir-rx51: Use 64-bit division macro
pwm: clps711x: Use 64-bit division macro
pwm: pwm-imx-tpm: Use 64-bit division macro
pwm: imx27: Use 64-bit division macro and function
pwm: sifive: Use 64-bit division macro
pwm: stm32-lp: Use %llu format specifier for period
pwm: sun4i: Use 64-bit division function
backlight: pwm_bl: Use 64-bit division function
pwm: core: Convert period and duty cycle to u64

 drivers/gpu/drm/i915/display/intel_panel.c |  2 +-
 drivers/hwmon/pwm-fan.c                    |  2 +-
 drivers/media/rc/ir-rx51.c                 |  3 ++-
 drivers/pwm/core.c                         |  4 ++--
 drivers/pwm/pwm-clps711x.c                 |  2 +-
 drivers/pwm/pwm-imx-tpm.c                  |  2 +-
 drivers/pwm/pwm-imx27.c                    |  5 ++---
 drivers/pwm/pwm-sifive.c                   |  2 +-
 drivers/pwm/pwm-stm32-lp.c                 |  2 +-
 drivers/pwm/pwm-sun4i.c                    |  2 +-
 drivers/pwm/sysfs.c                        |  8 ++++----
 drivers/video/backlight/pwm_bl.c           |  3 ++-
 include/linux/pwm.h                        | 12 ++++++------
 13 files changed, 25 insertions(+), 24 deletions(-)
Cc Lee Jones <[email protected]>
Cc Daniel Thompson <[email protected]>
Cc Jingoo Han <[email protected]>
Cc Bartlomiej Zolnierkiewicz <[email protected]>
Cc Maxime Ripard <[email protected]>
Cc Chen-Yu Tsai <[email protected]>
Cc Philipp Zabel <[email protected]>
Cc Fabrice Gasnier <[email protected]>
Cc Maxime Coquelin <[email protected]>
Cc Alexandre Torgue <[email protected]>
Cc Palmer Dabbelt <[email protected]>
Cc Paul Walmsley <[email protected]>
Cc Yash Shah <[email protected]>
Cc Atish Patra <[email protected]>
Cc Shawn Guo <[email protected]>
Cc Sascha Hauer <[email protected]>
Cc Pengutronix Kernel Team <[email protected]>
Cc Fabio Estevam <[email protected]>
Cc NXP Linux Team <[email protected]>
Cc Sascha Hauer <[email protected]>
Cc Pengutronix Kernel Team <[email protected]>
Cc Fabio Estevam <[email protected]>
Cc NXP Linux Team <[email protected]>
Cc Alexander Shiyan <[email protected]>
Cc Mauro Carvalho Chehab <[email protected]>
Cc Richard Fontana <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Kate Stewart <[email protected]>
Cc Allison Randal <[email protected]>
Cc Kamil Debski <[email protected]>
Cc Bartlomiej Zolnierkiewicz <[email protected]>
Cc Jean Delvare <[email protected]>
Cc Guenter Roeck <[email protected]>
Cc Liam Girdwood <[email protected]>
Cc Mark Brown <[email protected]>
Cc Jani Nikula <[email protected]>
Cc Joonas Lahtinen <[email protected]>
Cc David Airlie <[email protected]>
Cc Daniel Vetter <[email protected]>
Cc Chris Wilson <[email protected]>
Cc "Ville Syrjälä" <[email protected]>
Cc Michael Turquette <[email protected]>
Cc Stephen Boyd <[email protected]>
Cc Rodrigo Vivi <[email protected]>
Cc Maarten Lankhorst <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Mukesh Ojha <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Anson Huang <[email protected]>
Cc Gerald Baeza <[email protected]>
Cc Benjamin Gaignard <[email protected]>
Cc Axel Lin <[email protected]>
Cc Ding Xiang <[email protected]>
Cc Wesley W. Terpstra <[email protected]>
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
#1 lore raw

PATCH v9 1/11 drm/i915: Use 64-bit division macro

Since the PWM framework is switching struct pwm_state.duty_cycle's datatype to u64, prepare for this transition by using DIV_ROUND_UP_ULL to handle a 64-bit dividend.

Cc Jani Nikula <[email protected]>
Cc Joonas Lahtinen <[email protected]>
Cc David Airlie <[email protected]>
Cc Daniel Vetter <[email protected]>
Cc Chris Wilson <[email protected]>
Cc "Ville Syrjälä" <[email protected]>
Cc Rodrigo Vivi <[email protected]>
Cc Maarten Lankhorst <[email protected]>
---
 drivers/gpu/drm/i915/display/intel_panel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/gpu/drm/i915/display/intel_panel.c +1 -1
index bc14e9c..843cac1 100644
@@ -1868,7 +1868,7 @@ static int pwm_setup_backlight(struct intel_connector *connector,
 
 	panel->backlight.min = 0; /* 0% */
 	panel->backlight.max = 100; /* 100% */
-	panel->backlight.level = DIV_ROUND_UP(
+	panel->backlight.level = DIV_ROUND_UP_ULL(
 				 pwm_get_duty_cycle(panel->backlight.pwm) * 100,
 				 CRC_PMIC_PWM_PERIOD_NS);
 	panel->backlight.enabled = panel->backlight.level != 0;
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
maintainer Reviewed-by on v9 1/11
#2 lore raw

Re: [PATCH v9 01/11] drm/i915: Use 64-bit division macro

Quoted 15 lines · Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.duty_cycle's datatype to u64, prepare for this transition by using DIV_ROUND_UP_ULL to handle a 64-bit dividend.

Cc Jani Nikula <[email protected]>
Cc Joonas Lahtinen <[email protected]>
Cc David Airlie <[email protected]>
Cc Daniel Vetter <[email protected]>
Cc Chris Wilson <[email protected]>
Cc "Ville Syrjälä" <[email protected]>
Cc Rodrigo Vivi <[email protected]>
Cc Maarten Lankhorst <[email protected]>
Quoted 1 line

Also ack for merging this via whichever tree you prefer; please let me know if you want me to take this via drm-intel.

Quoted 17 lines
---
 drivers/gpu/drm/i915/display/intel_panel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/gpu/drm/i915/display/intel_panel.c +1 -1
index bc14e9c..843cac1 100644
@@ -1868,7 +1868,7 @@ static int pwm_setup_backlight(struct intel_connector *connector,
 
 	panel->backlight.min = 0; /* 0% */
 	panel->backlight.max = 100; /* 100% */
-	panel->backlight.level = DIV_ROUND_UP(
+	panel->backlight.level = DIV_ROUND_UP_ULL(
 				 pwm_get_duty_cycle(panel->backlight.pwm) * 100,
 				 CRC_PMIC_PWM_PERIOD_NS);
 	panel->backlight.enabled = panel->backlight.level != 0;
Signature · 1 line
Jani Nikula, Intel Open Source Graphics Center
#3 lore raw

Re: [PATCH v9 01/11] drm/i915: Use 64-bit division macro

Quoted 16 lines · Jani Nikula
Quoted 15 lines · Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.duty_cycle's datatype to u64, prepare for this transition by using DIV_ROUND_UP_ULL to handle a 64-bit dividend.

Cc Jani Nikula <[email protected]>
Cc Joonas Lahtinen <[email protected]>
Cc David Airlie <[email protected]>
Cc Daniel Vetter <[email protected]>
Cc Chris Wilson <[email protected]>
Cc "Ville Syrjälä" <[email protected]>
Cc Rodrigo Vivi <[email protected]>
Cc Maarten Lankhorst <[email protected]>
Quoted 3 lines
Quoted 1 line

Thanks!

Quoted 2 lines

Also ack for merging this via whichever tree you prefer; please let me know if you want me to take this via drm-intel.

I'm not sure if this patch can be taken via drm-intel in isolation as it is part of a series... Will let you know if I need to make such a request.

Thank you.

Guru Das.

#4 lore raw

PATCH v9 2/11 hwmon: pwm-fan: Use 64-bit division macro

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_args.period's datatype to u64, prepare for this transition by using DIV_ROUND_UP_ULL to handle a 64-bit dividend.

Cc Kamil Debski <[email protected]>
Cc Bartlomiej Zolnierkiewicz <[email protected]>
Cc Jean Delvare <[email protected]>
Cc Guenter Roeck <[email protected]>
Cc Liam Girdwood <[email protected]>
Cc Mark Brown <[email protected]>
---
 drivers/hwmon/pwm-fan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/hwmon/pwm-fan.c +1 -1
index 42ffd2e..283423a 100644
@@ -437,7 +437,7 @@ static int pwm_fan_resume(struct device *dev)
 		return 0;
 
 	pwm_get_args(ctx->pwm, &pargs);
-	duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
+	duty = DIV_ROUND_UP_ULL(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
 	ret = pwm_config(ctx->pwm, duty, pargs.period);
 	if (ret)
 		return ret;
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
#5 lore raw

PATCH v9 3/11 ir-rx51: Use 64-bit division macro

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using DIV_ROUND_CLOSEST_ULL to handle a 64-bit dividend.

Cc Mauro Carvalho Chehab <[email protected]>
Cc Richard Fontana <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Kate Stewart <[email protected]>
Cc Allison Randal <[email protected]>
---
 drivers/media/rc/ir-rx51.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
drivers/media/rc/ir-rx51.c +2 -1
index 8574eda..9a5dfd7 100644
@@ -241,7 +241,8 @@ static int ir_rx51_probe(struct platform_device *dev)
 	}
 
 	/* Use default, in case userspace does not set the carrier */
-	ir_rx51.freq = DIV_ROUND_CLOSEST(pwm_get_period(pwm), NSEC_PER_SEC);
+	ir_rx51.freq = DIV_ROUND_CLOSEST_ULL(pwm_get_period(pwm),
+			NSEC_PER_SEC);
 	pwm_put(pwm);
 
 	hrtimer_init(&ir_rx51.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
#6 lore raw

PATCH v9 4/11 pwm: clps711x: Use 64-bit division macro

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_args.period's datatype to u64, prepare for this transition by using DIV64_U64_ROUND_CLOSEST to handle a 64-bit divisor.

Cc Alexander Shiyan <[email protected]>
Cc Arnd Bergmann <[email protected]>
---
 drivers/pwm/pwm-clps711x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-clps711x.c +1 -1
index 924d39a..ba9500a 100644
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
 {
 	/* Duty cycle 0..15 max */
-	return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+	return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }
 
 static int clps711x_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
#7 lore raw

Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro

Quoted 18 lines · Guru Das Srinagesh

Since the PWM framework is switching struct pwm_args.period's datatype to u64, prepare for this transition by using DIV64_U64_ROUND_CLOSEST to handle a 64-bit divisor.

Cc Alexander Shiyan <[email protected]>
Cc Arnd Bergmann <[email protected]>
---
 drivers/pwm/pwm-clps711x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-clps711x.c +0 -0
index 924d39a..ba9500a 100644

drivers/pwm/pwm-clps711x.c static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v) · line 47

Quoted 6 lines
drivers/pwm/pwm-clps711x.c +1 -1
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
 {
        /* Duty cycle 0..15 max */
-       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }

Is it actually going to exceed U32_MAX? If not, a type cast may be more appropriate here than the expensive 64-bit division.

Arnd

#8 lore raw

Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro

Quoted 6 lines · Arnd Bergmann
Quoted 6 lines
drivers/pwm/pwm-clps711x.c +0 -0
index 924d39a..ba9500a 100644
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
Quoted 8 lines

drivers/pwm/pwm-clps711x.c static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v) · line 47

Quoted 5 lines
drivers/pwm/pwm-clps711x.c +1 -1
 {
        /* Duty cycle 0..15 max */
-       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }

Is it actually going to exceed U32_MAX? If not, a type cast may be more appropriate here than the expensive 64-bit division.

With the final change in this patch series, the framework will support periods that exceed U32_MAX. My concern is that using a typecast would mean that in those cases, this driver will not support > U32_MAX values. Using DIV64_U64_ROUND_CLOSEST makes the driver future proof and able to handle > U32_MAX values correctly. What do you think?

Thank you.

Guru Das.

#9 lore raw

Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro

Quoted 17 lines · Guru Das Srinagesh
Quoted 6 lines · Arnd Bergmann
Quoted 6 lines
drivers/pwm/pwm-clps711x.c +0 -0
index 924d39a..ba9500a 100644
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
Quoted 8 lines

drivers/pwm/pwm-clps711x.c static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v) · line 47

Quoted 5 lines
drivers/pwm/pwm-clps711x.c +1 -1
 {
        /* Duty cycle 0..15 max */
-       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }

Is it actually going to exceed U32_MAX? If not, a type cast may be more appropriate here than the expensive 64-bit division.

Quoted 5 lines

With the final change in this patch series, the framework will support periods that exceed U32_MAX. My concern is that using a typecast would mean that in those cases, this driver will not support > U32_MAX values. Using DIV64_U64_ROUND_CLOSEST makes the driver future proof and able to handle > U32_MAX values correctly. What do you think?

Ah, so if the period can actually be larger than U32_MAX, you need to handle that case. However, I see that the divident in this code (v * 0xf) is still a 32-bit number, so a correct and efficient implementation could be

   if (pwm->args.period > (UINT_MAX / 0xf))
          return 0;
   return DIV_ROUND_CLOSEST(v * 0xf, (u32)pwm->args.period);

Arnd

#10 lore raw

Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro

Quoted 25 lines · Arnd Bergmann
Quoted 17 lines · Guru Das Srinagesh
Quoted 6 lines · Arnd Bergmann
Quoted 6 lines
drivers/pwm/pwm-clps711x.c +0 -0
index 924d39a..ba9500a 100644
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
Quoted 8 lines

drivers/pwm/pwm-clps711x.c static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v) · line 47

Quoted 5 lines
drivers/pwm/pwm-clps711x.c +1 -1
 {
        /* Duty cycle 0..15 max */
-       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }

Is it actually going to exceed U32_MAX? If not, a type cast may be more appropriate here than the expensive 64-bit division.

Quoted 5 lines

With the final change in this patch series, the framework will support periods that exceed U32_MAX. My concern is that using a typecast would mean that in those cases, this driver will not support > U32_MAX values. Using DIV64_U64_ROUND_CLOSEST makes the driver future proof and able to handle > U32_MAX values correctly. What do you think?

Quoted 5 lines

Ah, so if the period can actually be larger than U32_MAX, you need to handle that case. However, I see that the divident in this code (v * 0xf) is still a 32-bit number, so a correct and efficient implementation could be

   if (pwm->args.period > (UINT_MAX / 0xf))

Shouldn't the if condition be the following? Or am I missing something here?

     if (pwm->args.period > (UINT_MAX / (v * 0xf)))
     					^^^^^^^^^
Quoted 2 lines
          return 0;

return DIV_ROUND_CLOSEST(v * 0xf, (u32)pwm->args.period);

Thank you.

Guru Das.

#11 lore raw

Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro

Quoted 31 lines · Guru Das Srinagesh
Quoted 29 lines · Arnd Bergmann
Quoted 17 lines · Guru Das Srinagesh
Quoted 6 lines · Arnd Bergmann
Quoted 6 lines
drivers/pwm/pwm-clps711x.c +0 -0
index 924d39a..ba9500a 100644
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
Quoted 8 lines

drivers/pwm/pwm-clps711x.c static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v) · line 47

Quoted 5 lines
drivers/pwm/pwm-clps711x.c +1 -1
 {
        /* Duty cycle 0..15 max */
-       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }

Is it actually going to exceed U32_MAX? If not, a type cast may be more appropriate here than the expensive 64-bit division.

Quoted 5 lines

With the final change in this patch series, the framework will support periods that exceed U32_MAX. My concern is that using a typecast would mean that in those cases, this driver will not support > U32_MAX values. Using DIV64_U64_ROUND_CLOSEST makes the driver future proof and able to handle > U32_MAX values correctly. What do you think?

Ah, so if the period can actually be larger than U32_MAX, you need to handle that case. However, I see that the divident in this code (v * 0xf) is still a 32-bit number, so a correct and efficient implementation could be

Quoted 7 lines
Quoted 1 line
   if (pwm->args.period > (UINT_MAX / 0xf))

Shouldn't the if condition be the following? Or am I missing something here?

     if (pwm->args.period > (UINT_MAX / (v * 0xf)))
                                        ^^^^^^^^^

That would require performing a division, which is an external function call on ARMv4. My version just checks for an upper bound and completely avoids the division. You could also just check for ">UINT_MAX" if you find that clearer.

Arnd

#12 lore raw

Re: [PATCH v9 04/11] pwm: clps711x: Use 64-bit division macro

Quoted 37 lines · Arnd Bergmann
Quoted 36 lines · Guru Das Srinagesh
Quoted 25 lines · Arnd Bergmann
Quoted 17 lines · Guru Das Srinagesh
Quoted 6 lines · Arnd Bergmann
Quoted 6 lines
drivers/pwm/pwm-clps711x.c +0 -0
index 924d39a..ba9500a 100644
@@ -43,7 +43,7 @@ static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v)
 static unsigned int clps711x_get_duty(struct pwm_device *pwm, unsigned int v)
Quoted 8 lines

drivers/pwm/pwm-clps711x.c static void clps711x_pwm_update_val(struct clps711x_chip *priv, u32 n, u32 v) · line 47

Quoted 5 lines
drivers/pwm/pwm-clps711x.c +1 -1
 {
        /* Duty cycle 0..15 max */
-       return DIV_ROUND_CLOSEST(v * 0xf, pwm->args.period);
+       return DIV64_U64_ROUND_CLOSEST(v * 0xf, pwm->args.period);
 }

Is it actually going to exceed U32_MAX? If not, a type cast may be more appropriate here than the expensive 64-bit division.

Quoted 5 lines

With the final change in this patch series, the framework will support periods that exceed U32_MAX. My concern is that using a typecast would mean that in those cases, this driver will not support > U32_MAX values. Using DIV64_U64_ROUND_CLOSEST makes the driver future proof and able to handle > U32_MAX values correctly. What do you think?

Quoted 5 lines

Ah, so if the period can actually be larger than U32_MAX, you need to handle that case. However, I see that the divident in this code (v * 0xf) is still a 32-bit number, so a correct and efficient implementation could be

   if (pwm->args.period > (UINT_MAX / 0xf))

Shouldn't the if condition be the following? Or am I missing something here?

Quoted 7 lines
Quoted 2 lines
     if (pwm->args.period > (UINT_MAX / (v * 0xf)))
                                        ^^^^^^^^^

That would require performing a division, which is an external function call on ARMv4. My version just checks for an upper bound and completely avoids the division. You could also just check for ">UINT_MAX" if you find that clearer.

Thanks, have checked for UINT_MAX in v10 of my patchset that I just uploaded. Could you please review it?

Thank you.

Guru Das.

#13 lore raw

PATCH v9 5/11 pwm: pwm-imx-tpm: Use 64-bit division macro

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using DIV64_U64_ROUND_CLOSEST to handle a 64-bit divisor.

Cc Shawn Guo <[email protected]>
Cc Sascha Hauer <[email protected]>
Cc Pengutronix Kernel Team <[email protected]>
Cc Fabio Estevam <[email protected]>
Cc NXP Linux Team <[email protected]>
Cc Anson Huang <[email protected]>
---
 drivers/pwm/pwm-imx-tpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-imx-tpm.c +1 -1
index 9145f61..53bf364 100644
@@ -126,7 +126,7 @@ static int pwm_imx_tpm_round_state(struct pwm_chip *chip,
 		real_state->duty_cycle = state->duty_cycle;
 
 	tmp = (u64)p->mod * real_state->duty_cycle;
-	p->val = DIV_ROUND_CLOSEST_ULL(tmp, real_state->period);
+	p->val = DIV64_U64_ROUND_CLOSEST(tmp, real_state->period);
 
 	real_state->polarity = state->polarity;
 	real_state->enabled = state->enabled;
Signature · 2 lines
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a Linux Foundation Collaborative Project
#14 lore raw

PATCH v9 6/11 pwm: imx27: Use 64-bit division macro and function

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using DIV_ROUND_UP_ULL to handle a 64-bit dividend, and div64_u64 to handle a 64-bit divisor.

Cc Shawn Guo <[email protected]>
Cc Sascha Hauer <[email protected]>
Cc Pengutronix Kernel Team <[email protected]>
Cc Fabio Estevam <[email protected]>
Cc NXP Linux Team <[email protected]>
Cc Anson Huang <[email protected]>
Cc Michal Vokáč <[email protected]>
Cc Adam Ford <[email protected]>
Cc Mukesh Ojha <[email protected]>
Cc Dan Carpenter <[email protected]>
---
 drivers/pwm/pwm-imx27.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
drivers/pwm/pwm-imx27.c +2 -3
index 35a7ac42..b7d38d0 100644
@@ -208,7 +208,7 @@ static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip,
 	sr = readl(imx->mmio_base + MX3_PWMSR);
 	fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);
 	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
-		period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
+		period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm),
 					 NSEC_PER_MSEC);
 		msleep(period_ms);
 
@@ -240,8 +240,7 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	period_cycles /= prescale;
 	c = (unsigned long long)period_cycles * state->duty_cycle;
-	do_div(c, state->period);
-	duty_cycles = c;
+	duty_cycles = div64_u64(c, state->period);
 
 	/*
 	 * according to imx pwm RM, the real period value should be PERIOD
Signature · 2 lines
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a Linux Foundation Collaborative Project
#15 lore raw

PATCH v9 7/11 pwm: sifive: Use 64-bit division macro

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_args.period's datatype to u64, prepare for this transition by using DIV64_U64_ROUND_CLOSEST to handle a 64-bit divisor.

Cc Palmer Dabbelt <[email protected]>
Cc Paul Walmsley <[email protected]>
Cc Yash Shah <[email protected]>
Cc Atish Patra <[email protected]>
Cc Ding Xiang <[email protected]>
Cc Wesley W. Terpstra <[email protected]>
---
 drivers/pwm/pwm-sifive.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-sifive.c +1 -1
index cc63f9b..62de0bb 100644
@@ -181,7 +181,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * consecutively
 	 */
 	num = (u64)duty_cycle * (1U << PWM_SIFIVE_CMPWIDTH);
-	frac = DIV_ROUND_CLOSEST_ULL(num, state->period);
+	frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
 	/* The hardware cannot generate a 100% duty cycle */
 	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
 
Signature · 2 lines
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a Linux Foundation Collaborative Project
#16 lore raw

PATCH v9 8/11 pwm: stm32-lp: Use %llu format specifier for period

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_args.period's datatype to u64, prepare for this transition by using the right specifier for printing a 64-bit value.

Cc Fabrice Gasnier <[email protected]>
Cc Maxime Coquelin <[email protected]>
Cc Alexandre Torgue <[email protected]>
Cc Gerald Baeza <[email protected]>
Cc Benjamin Gaignard <[email protected]>
Cc Axel Lin <[email protected]>
---
 drivers/pwm/pwm-stm32-lp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-stm32-lp.c +1 -1
index 67fca62..134c146 100644
@@ -61,7 +61,7 @@ static int stm32_pwm_lp_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	do_div(div, NSEC_PER_SEC);
 	if (!div) {
 		/* Clock is too slow to achieve requested period. */
-		dev_dbg(priv->chip.dev, "Can't reach %u ns\n",	state->period);
+		dev_dbg(priv->chip.dev, "Can't reach %llu ns\n", state->period);
 		return -EINVAL;
 	}
 
Signature · 2 lines
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a Linux Foundation Collaborative Project
#17 lore raw

PATCH v9 9/11 pwm: sun4i: Use 64-bit division function

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using div_u64 to handle a 64-bit dividend instead of a straight division operation.

Cc Maxime Ripard <[email protected]>
Cc Chen-Yu Tsai <[email protected]>
Cc Philipp Zabel <[email protected]>
---
 drivers/pwm/pwm-sun4i.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-sun4i.c +1 -1
index 3e3efa6..772fdf4 100644
@@ -286,7 +286,7 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	val = (duty & PWM_DTY_MASK) | PWM_PRD(period);
 	sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
 	sun4i_pwm->next_period[pwm->hwpwm] = jiffies +
-		usecs_to_jiffies(cstate.period / 1000 + 1);
+		usecs_to_jiffies(div_u64(cstate.period, 1000) + 1);
 	sun4i_pwm->needs_delay[pwm->hwpwm] = true;
 
 	if (state->polarity != PWM_POLARITY_NORMAL)
Signature · 2 lines
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a Linux Foundation Collaborative Project
#18 lore raw

PATCH v9 10/11 backlight: pwm_bl: Use 64-bit division function

In reply to Guru Das Srinagesh

Since the PWM framework is switching struct pwm_state.period's datatype to u64, prepare for this transition by using div_u64 to handle a 64-bit dividend instead of a straight division operation.

Cc Lee Jones <[email protected]>
Cc Daniel Thompson <[email protected]>
Cc Jingoo Han <[email protected]>
Cc Bartlomiej Zolnierkiewicz <[email protected]>
---
 drivers/video/backlight/pwm_bl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
drivers/video/backlight/pwm_bl.c +2 -1
index efb4efc..3e5dbcf 100644
@@ -625,7 +625,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		pb->scale = data->max_brightness;
 	}
 
-	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
+	pb->lth_brightness = data->lth_brightness * (div_u64(state.period,
+				pb->scale));
 
 	props.type = BACKLIGHT_RAW;
 	props.max_brightness = data->max_brightness;
Signature · 2 lines
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a Linux Foundation Collaborative Project
#19 lore raw

PATCH v9 11/11 pwm: core: Convert period and duty cycle to u64

In reply to Guru Das Srinagesh

Because period and duty cycle are defined as ints with units of nanoseconds, the maximum time duration that can be set is limited to ~2.147 seconds. Change their definitions to u64 in the structs of the PWM framework so that higher durations may be set.

---
 drivers/pwm/core.c  |  4 ++--
 drivers/pwm/sysfs.c |  8 ++++----
 include/linux/pwm.h | 12 ++++++------
 3 files changed, 12 insertions(+), 12 deletions(-)
drivers/pwm/core.c +2 -2
index 5a7f659..81aa3c2 100644
@@ -1163,8 +1163,8 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 		if (state.enabled)
 			seq_puts(s, " enabled");
 
-		seq_printf(s, " period: %u ns", state.period);
-		seq_printf(s, " duty: %u ns", state.duty_cycle);
+		seq_printf(s, " period: %llu ns", state.period);
+		seq_printf(s, " duty: %llu ns", state.duty_cycle);
 		seq_printf(s, " polarity: %s",
 			   state.polarity ? "inverse" : "normal");
 
drivers/pwm/sysfs.c +4 -4
index 2389b86..449dbc0 100644
@@ -42,7 +42,7 @@ static ssize_t period_show(struct device *child,
 
 	pwm_get_state(pwm, &state);
 
-	return sprintf(buf, "%u\n", state.period);
+	return sprintf(buf, "%llu\n", state.period);
 }
 
 static ssize_t period_store(struct device *child,
@@ -52,10 +52,10 @@ static ssize_t period_store(struct device *child,
 	struct pwm_export *export = child_to_pwm_export(child);
 	struct pwm_device *pwm = export->pwm;
 	struct pwm_state state;
-	unsigned int val;
+	u64 val;
 	int ret;
 
-	ret = kstrtouint(buf, 0, &val);
+	ret = kstrtou64(buf, 0, &val);
 	if (ret)
 		return ret;
 
@@ -77,7 +77,7 @@ static ssize_t duty_cycle_show(struct device *child,
 
 	pwm_get_state(pwm, &state);
 
-	return sprintf(buf, "%u\n", state.duty_cycle);
+	return sprintf(buf, "%llu\n", state.duty_cycle);
 }
 
 static ssize_t duty_cycle_store(struct device *child,
include/linux/pwm.h +6 -6
index 0ef808d..b53f13d 100644
@@ -39,7 +39,7 @@ enum pwm_polarity {
  * current PWM hardware state.
  */
 struct pwm_args {
-	unsigned int period;
+	u64 period;
 	enum pwm_polarity polarity;
 };
 
@@ -56,8 +56,8 @@ enum {
  * @enabled: PWM enabled status
  */
 struct pwm_state {
-	unsigned int period;
-	unsigned int duty_cycle;
+	u64 period;
+	u64 duty_cycle;
 	enum pwm_polarity polarity;
 	bool enabled;
 };
@@ -105,13 +105,13 @@ static inline bool pwm_is_enabled(const struct pwm_device *pwm)
 	return state.enabled;
 }
 
-static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
+static inline void pwm_set_period(struct pwm_device *pwm, u64 period)
 {
 	if (pwm)
 		pwm->state.period = period;
 }
 
-static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
+static inline u64 pwm_get_period(const struct pwm_device *pwm)
 {
 	struct pwm_state state;
 
@@ -126,7 +126,7 @@ static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
 		pwm->state.duty_cycle = duty;
 }
 
-static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
+static inline u64 pwm_get_duty_cycle(const struct pwm_device *pwm)
 {
 	struct pwm_state state;
 
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
#20 lore raw

Re: [PATCH v9 11/11] pwm: core: Convert period and duty cycle to u64

Thank you for the patch! Yet something to improve:

Hi Guru,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on pwm/for-next]
[also build test ERROR on hwmon/hwmon-next linuxtv-media/master shawnguo/for-next stm32/stm32-next sunxi/sunxi/for-next v5.6-rc6] [cannot apply to drm-intel/for-linux-next next-20200317]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Guru-Das-Srinagesh/Convert-PWM-period-and-duty-cycle-to-u64/20200318-094102
base:   https://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm.git for-next
config: microblaze-randconfig-a001-20200318 (attached as .config)
compiler: microblaze-linux-gcc (GCC) 9.2.0

reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=9.2.0 make.cross ARCH=microblaze

If you fix the issue, kindly add following tag

All errors (new ones prefixed by >>):

microblaze-linux-ld: drivers/clk/clk-pwm.o: in function `clk_pwm_probe':

>> drivers/clk/clk-pwm.c:92: undefined reference to `__udivdi3'

.exit.data' referenced in section .exit.text' of drivers/tty/n_hdlc.o: defined in discarded section .exit.data' of drivers/tty/n_hdlc.o .exit.data' referenced in section .exit.text' of drivers/tty/n_hdlc.o: defined in discarded section .exit.data' of drivers/tty/n_hdlc.o

vim +92 drivers/clk/clk-pwm.c

9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   66  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   67  static int clk_pwm_probe(struct platform_device *pdev)
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   68  {
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   69  	struct device_node *node = pdev->dev.of_node;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   70  	struct clk_init_data init;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   71  	struct clk_pwm *clk_pwm;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   72  	struct pwm_device *pwm;
dd0b38b7ca0d8c Boris Brezillon 2016-04-14   73  	struct pwm_args pargs;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   74  	const char *clk_name;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   75  	int ret;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   76  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   77  	clk_pwm = devm_kzalloc(&pdev->dev, sizeof(*clk_pwm), GFP_KERNEL);
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   78  	if (!clk_pwm)
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   79  		return -ENOMEM;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   80  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   81  	pwm = devm_pwm_get(&pdev->dev, NULL);
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   82  	if (IS_ERR(pwm))
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   83  		return PTR_ERR(pwm);
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   84  
dd0b38b7ca0d8c Boris Brezillon 2016-04-14   85  	pwm_get_args(pwm, &pargs);
dd0b38b7ca0d8c Boris Brezillon 2016-04-14   86  	if (!pargs.period) {
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   87  		dev_err(&pdev->dev, "invalid PWM period\n");
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   88  		return -EINVAL;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   89  	}
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   90  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   91  	if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  @92  		clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   93  
dd0b38b7ca0d8c Boris Brezillon 2016-04-14   94  	if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
dd0b38b7ca0d8c Boris Brezillon 2016-04-14   95  	    pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   96  		dev_err(&pdev->dev,
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   97  			"clock-frequency does not match PWM period\n");
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   98  		return -EINVAL;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13   99  	}
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  100  
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  101  	/*
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  102  	 * FIXME: pwm_apply_args() should be removed when switching to the
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  103  	 * atomic PWM API.
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  104  	 */
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  105  	pwm_apply_args(pwm);
dd0b38b7ca0d8c Boris Brezillon 2016-04-14  106  	ret = pwm_config(pwm, (pargs.period + 1) >> 1, pargs.period);
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  107  	if (ret < 0)
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  108  		return ret;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  109  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  110  	clk_name = node->name;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  111  	of_property_read_string(node, "clock-output-names", &clk_name);
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  112  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  113  	init.name = clk_name;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  114  	init.ops = &clk_pwm_ops;
90b6c5c73c6904 Stephen Boyd    2019-04-25  115  	init.flags = 0;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  116  	init.num_parents = 0;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  117  
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  118  	clk_pwm->pwm = pwm;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  119  	clk_pwm->hw.init = &init;
4cf915dfb8ede6 Stephen Boyd    2016-06-01  120  	ret = devm_clk_hw_register(&pdev->dev, &clk_pwm->hw);
4cf915dfb8ede6 Stephen Boyd    2016-06-01  121  	if (ret)
4cf915dfb8ede6 Stephen Boyd    2016-06-01  122  		return ret;
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  123  
4cf915dfb8ede6 Stephen Boyd    2016-06-01  124  	return of_clk_add_hw_provider(node, of_clk_hw_simple_get, &clk_pwm->hw);
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  125  }
9a74ccdbbb8fa6 Philipp Zabel   2015-02-13  126  

:::::: The code at line 92 was first introduced by commit
:::::: dd0b38b7ca0d8c8aadcf8a17d7c90d36ab8ab6e4 clk: pwm: Use pwm_get_args() where appropriate

:::::: TO: Boris Brezillon <[email protected]> :::::: CC: Thierry Reding <[email protected]>

---
0-DAY CI Kernel Test Service, Intel Corporation
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