[PATCH v2 0/3] pwm: pwm-samsung: fix suspend/resume support

[PATCH v2 0/3] pwm: pwm-samsung: fix suspend/resume support

[Bartlomiej Zolnierkiewicz]

Hi,

This patchset fixes suspend/resume support in pwm-samsung
driver (which has an effect of fixing suspend/resume support
for PWM client drivers such as pwm-fan one). Then it removes
no longer needed suspend/resume code from pwm-fan driver.

It was tested on Odroid-XU3 board (with few extra patches
adding SoC/board suspend/resume support which are not in
upstream yet).

The initial issue that has been observed on this configuration
was that after suspend/resume operation the fan was turned on
(while the thermal code had explicitly disabled the fan by
calling back into pwm-fan driver before the suspend/resume).

Fixing this in the pwm-fan driver itself is not feasible since
pwm_config()/pwm_disable() & co. API saves information about
current state and doesn't pass the relevant values to PWM core
if they are identical to the ones used previously (moreover PWM
core itself does the same before calling into the PWM hardware
driver).

Changes since v1
(https://www.spinics.net/lists/kernel/msg2480445.html):
- added Acked-by from Guenter to patch #3
- fixed patch #2 to use the right variable (chip -> our_chip)

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics


Bartlomiej Zolnierkiewicz (3):
  pwm: pwm-samsung: remove redundant checks from pwm_samsung_config()
  pwm: pwm-samsung: fix suspend/resume support
  hwmon: pwm-fan: remove no longer needed suspend/resume code

 drivers/hwmon/pwm-fan.c   | 32 ----------------------
 drivers/pwm/pwm-samsung.c | 70 +++++++++++++++++++++++------------------------
 2 files changed, 35 insertions(+), 67 deletions(-)

-- 
1.9.1

[PATCH v2 1/3] pwm: pwm-samsung: remove redundant checks from pwm_samsung_config()

[Bartlomiej Zolnierkiewicz]

If the requested period_ns and duty_ns values are identical to
the last programmed ones pwm_samsung_config() returns early and
skips the hardware configuration. The same checks are now done
by the PWM core so the driver specific ones can be removed.

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/pwm/pwm-samsung.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
index f113cda..9ea7638 100644
--- a/drivers/pwm/pwm-samsung.c
+++ b/drivers/pwm/pwm-samsung.c
@@ -312,9 +312,6 @@ static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (period_ns > NSEC_PER_SEC)
 		return -ERANGE;
 
-	if (period_ns == chan->period_ns && duty_ns == chan->duty_ns)
-		return 0;
-
 	tcnt = readl(our_chip->base + REG_TCNTB(pwm->hwpwm));
 	oldtcmp = readl(our_chip->base + REG_TCMPB(pwm->hwpwm));
 
-- 
1.9.1

Re: [PATCH v2 1/3] pwm: pwm-samsung: remove redundant checks from pwm_samsung_config()

[Thierry Reding]

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On Mon, Apr 24, 2017 at 12:01:07PM +0200, Bartlomiej Zolnierkiewicz wrote:
> If the requested period_ns and duty_ns values are identical to
> the last programmed ones pwm_samsung_config() returns early and
> skips the hardware configuration. The same checks are now done
> by the PWM core so the driver specific ones can be removed.
> 
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  drivers/pwm/pwm-samsung.c | 3 ---
>  1 file changed, 3 deletions(-)

Applied to for-4.14/drivers, thanks.

Thierry

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[PATCH v2 2/3] pwm: pwm-samsung: fix suspend/resume support

[Bartlomiej Zolnierkiewicz]

Fix suspend/resume support:

- add disabled_mask to struct samsung_pwm_chip to track PWM
  disabled state information in pwm_samsung_{disable,enable}()

- rename pwm_samsung_config() to __pwm_samsung_config() and
  add extra force_period parameter to be used during resume
  (to force tin_ns and tcnt recalculation)

- add pwm_samsung_config() wrapper for preserving old behavior

- properly restore PWM configuration in pwm_samsung_resume()

- remove no longer needed pwm_samsung_suspend()

- update Copyrights

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
---
 drivers/pwm/pwm-samsung.c | 67 +++++++++++++++++++++++++----------------------
 1 file changed, 35 insertions(+), 32 deletions(-)

diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
index 9ea7638..062f2cf 100644
--- a/drivers/pwm/pwm-samsung.c
+++ b/drivers/pwm/pwm-samsung.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2008 Simtec Electronics
  *     Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
  * Copyright (c) 2013 Tomasz Figa <tomasz.figa@gmail.com>
+ * Copyright (c) 2017 Samsung Electronics Co., Ltd.
  *
  * PWM driver for Samsung SoCs
  *
@@ -74,6 +75,7 @@ struct samsung_pwm_channel {
  * @chip:		generic PWM chip
  * @variant:		local copy of hardware variant data
  * @inverter_mask:	inverter status for all channels - one bit per channel
+ * @disabled_mask:	disabled status for all channels - one bit per channel
  * @base:		base address of mapped PWM registers
  * @base_clk:		base clock used to drive the timers
  * @tclk0:		external clock 0 (can be ERR_PTR if not present)
@@ -83,6 +85,7 @@ struct samsung_pwm_chip {
 	struct pwm_chip chip;
 	struct samsung_pwm_variant variant;
 	u8 inverter_mask;
+	u8 disabled_mask;
 
 	void __iomem *base;
 	struct clk *base_clk;
@@ -257,6 +260,8 @@ static int pwm_samsung_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	tcon |= TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan);
 	writel(tcon, our_chip->base + REG_TCON);
 
+	our_chip->disabled_mask &= ~BIT(pwm->hwpwm);
+
 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 
 	return 0;
@@ -275,6 +280,8 @@ static void pwm_samsung_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	tcon &= ~TCON_AUTORELOAD(tcon_chan);
 	writel(tcon, our_chip->base + REG_TCON);
 
+	our_chip->disabled_mask |= BIT(pwm->hwpwm);
+
 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }
 
@@ -297,8 +304,8 @@ static void pwm_samsung_manual_update(struct samsung_pwm_chip *chip,
 	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
 }
 
-static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			      int duty_ns, int period_ns)
+static int __pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
+				int duty_ns, int period_ns, bool force_period)
 {
 	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
 	struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
@@ -319,7 +326,7 @@ static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	++tcnt;
 
 	/* Check to see if we are changing the clock rate of the PWM. */
-	if (chan->period_ns != period_ns) {
+	if (chan->period_ns != period_ns || force_period) {
 		unsigned long tin_rate;
 		u32 period;
 
@@ -378,6 +385,12 @@ static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
+static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			      int duty_ns, int period_ns)
+{
+	return __pwm_samsung_config(chip, pwm, duty_ns, period_ns, false);
+}
+
 static void pwm_samsung_set_invert(struct samsung_pwm_chip *chip,
 				   unsigned int channel, bool invert)
 {
@@ -589,51 +602,41 @@ static int pwm_samsung_remove(struct platform_device *pdev)
 }
 
 #ifdef CONFIG_PM_SLEEP
-static int pwm_samsung_suspend(struct device *dev)
+static int pwm_samsung_resume(struct device *dev)
 {
-	struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
+	struct samsung_pwm_chip *our_chip = dev_get_drvdata(dev);
+	struct pwm_chip *chip = &our_chip->chip;
 	unsigned int i;
 
-	/*
-	 * No one preserves these values during suspend so reset them.
-	 * Otherwise driver leaves PWM unconfigured if same values are
-	 * passed to pwm_config() next time.
-	 */
-	for (i = 0; i < SAMSUNG_PWM_NUM; ++i) {
-		struct pwm_device *pwm = &chip->chip.pwms[i];
+	for (i = 0; i < SAMSUNG_PWM_NUM; i++) {
+		struct pwm_device *pwm = &chip->pwms[i];
 		struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
 
 		if (!chan)
 			continue;
 
-		chan->period_ns = 0;
-		chan->duty_ns = 0;
-	}
-
-	return 0;
-}
+		if (our_chip->variant.output_mask & BIT(i))
+			pwm_samsung_set_invert(our_chip, i,
+					our_chip->inverter_mask & BIT(i));
 
-static int pwm_samsung_resume(struct device *dev)
-{
-	struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
-	unsigned int chan;
+		if (chan->period_ns) {
+			__pwm_samsung_config(chip, pwm, chan->duty_ns,
+					     chan->period_ns, true);
+			/* needed to make PWM disable work on Odroid-XU3 */
+			pwm_samsung_manual_update(our_chip, pwm);
+		}
 
-	/*
-	 * Inverter setting must be preserved across suspend/resume
-	 * as nobody really seems to configure it more than once.
-	 */
-	for (chan = 0; chan < SAMSUNG_PWM_NUM; ++chan) {
-		if (chip->variant.output_mask & BIT(chan))
-			pwm_samsung_set_invert(chip, chan,
-					chip->inverter_mask & BIT(chan));
+		if (our_chip->disabled_mask & BIT(i))
+			pwm_samsung_disable(chip, pwm);
+		else
+			pwm_samsung_enable(chip, pwm);
 	}
 
 	return 0;
 }
 #endif
 
-static SIMPLE_DEV_PM_OPS(pwm_samsung_pm_ops, pwm_samsung_suspend,
-			 pwm_samsung_resume);
+static SIMPLE_DEV_PM_OPS(pwm_samsung_pm_ops, NULL, pwm_samsung_resume);
 
 static struct platform_driver pwm_samsung_driver = {
 	.driver		= {
-- 
1.9.1

Re: [PATCH v2 2/3] pwm: pwm-samsung: fix suspend/resume support

[Thierry Reding]

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On Mon, Apr 24, 2017 at 12:01:08PM +0200, Bartlomiej Zolnierkiewicz wrote:
> Fix suspend/resume support:
> 
> - add disabled_mask to struct samsung_pwm_chip to track PWM
>   disabled state information in pwm_samsung_{disable,enable}()
> 
> - rename pwm_samsung_config() to __pwm_samsung_config() and
>   add extra force_period parameter to be used during resume
>   (to force tin_ns and tcnt recalculation)
> 
> - add pwm_samsung_config() wrapper for preserving old behavior
> 
> - properly restore PWM configuration in pwm_samsung_resume()
> 
> - remove no longer needed pwm_samsung_suspend()
> 
> - update Copyrights
> 
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> ---
>  drivers/pwm/pwm-samsung.c | 67 +++++++++++++++++++++++++----------------------
>  1 file changed, 35 insertions(+), 32 deletions(-)

Applied to for-4.14/drivers, thanks.

Thierry

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[PATCH v2 3/3] hwmon: pwm-fan: remove no longer needed suspend/resume code

[Bartlomiej Zolnierkiewicz]

The suspend/resume is now properly handled by pwm-samsung driver
(pwm-fan is currently only used by ARM Exynos boards) and the old
code only handles ctx->pwm_value != 0 case. Just remove it.

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/pwm-fan.c | 32 --------------------------------
 1 file changed, 32 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index f9af393..9dc40f3 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -302,37 +302,6 @@ static int pwm_fan_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int pwm_fan_suspend(struct device *dev)
-{
-	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
-
-	if (ctx->pwm_value)
-		pwm_disable(ctx->pwm);
-	return 0;
-}
-
-static int pwm_fan_resume(struct device *dev)
-{
-	struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
-	struct pwm_args pargs;
-	unsigned long duty;
-	int ret;
-
-	if (ctx->pwm_value == 0)
-		return 0;
-
-	pwm_get_args(ctx->pwm, &pargs);
-	duty = DIV_ROUND_UP(ctx->pwm_value * (pargs.period - 1), MAX_PWM);
-	ret = pwm_config(ctx->pwm, duty, pargs.period);
-	if (ret)
-		return ret;
-	return pwm_enable(ctx->pwm);
-}
-#endif
-
-static SIMPLE_DEV_PM_OPS(pwm_fan_pm, pwm_fan_suspend, pwm_fan_resume);
-
 static const struct of_device_id of_pwm_fan_match[] = {
 	{ .compatible = "pwm-fan", },
 	{},
@@ -344,7 +313,6 @@ static int pwm_fan_resume(struct device *dev)
 	.remove		= pwm_fan_remove,
 	.driver	= {
 		.name		= "pwm-fan",
-		.pm		= &pwm_fan_pm,
 		.of_match_table	= of_pwm_fan_match,
 	},
 };
-- 
1.9.1

Re: [PATCH v2 0/3] pwm: pwm-samsung: fix suspend/resume support

[Bartlomiej Zolnierkiewicz]

ping. Could this patchset be merged for 4.13, please?

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

On Monday, April 24, 2017 12:01:06 PM Bartlomiej Zolnierkiewicz wrote:
> Hi,
> 
> This patchset fixes suspend/resume support in pwm-samsung
> driver (which has an effect of fixing suspend/resume support
> for PWM client drivers such as pwm-fan one). Then it removes
> no longer needed suspend/resume code from pwm-fan driver.
> 
> It was tested on Odroid-XU3 board (with few extra patches
> adding SoC/board suspend/resume support which are not in
> upstream yet).
> 
> The initial issue that has been observed on this configuration
> was that after suspend/resume operation the fan was turned on
> (while the thermal code had explicitly disabled the fan by
> calling back into pwm-fan driver before the suspend/resume).
> 
> Fixing this in the pwm-fan driver itself is not feasible since
> pwm_config()/pwm_disable() & co. API saves information about
> current state and doesn't pass the relevant values to PWM core
> if they are identical to the ones used previously (moreover PWM
> core itself does the same before calling into the PWM hardware
> driver).
> 
> Changes since v1
> (https://www.spinics.net/lists/kernel/msg2480445.html):
> - added Acked-by from Guenter to patch #3
> - fixed patch #2 to use the right variable (chip -> our_chip)
> 
> Best regards,
> --
> Bartlomiej Zolnierkiewicz
> Samsung R&D Institute Poland
> Samsung Electronics
> 
> 
> Bartlomiej Zolnierkiewicz (3):
>   pwm: pwm-samsung: remove redundant checks from pwm_samsung_config()
>   pwm: pwm-samsung: fix suspend/resume support
>   hwmon: pwm-fan: remove no longer needed suspend/resume code
> 
>  drivers/hwmon/pwm-fan.c   | 32 ----------------------
>  drivers/pwm/pwm-samsung.c | 70 +++++++++++++++++++++++------------------------
>  2 files changed, 35 insertions(+), 67 deletions(-)