[PATCH 1/3] pwm: Change prototype of .get_state() callback to return an error

[PATCH 1/3] pwm: Change prototype of .get_state() callback to return an error

[Uwe Kleine-König]

Most drivers succeed to read out the programmed state unconditionally.
But some don't, allow them to signal a failure to the pwm core.

All drivers are adapted to return 0 on success and forward the error
code otherwise.

The core doesn't make use of this yet.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/gpio/gpio-mvebu.c             |  9 ++++++---
 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 14 ++++++++------
 drivers/leds/rgb/leds-qcom-lpg.c      | 12 +++++++-----
 drivers/pwm/pwm-atmel.c               |  6 ++++--
 drivers/pwm/pwm-bcm-iproc.c           |  8 +++++---
 drivers/pwm/pwm-crc.c                 | 10 ++++++----
 drivers/pwm/pwm-cros-ec.c             | 12 ++++++------
 drivers/pwm/pwm-dwc.c                 |  6 ++++--
 drivers/pwm/pwm-hibvt.c               |  6 ++++--
 drivers/pwm/pwm-imx-tpm.c             |  8 +++++---
 drivers/pwm/pwm-imx27.c               |  8 +++++---
 drivers/pwm/pwm-intel-lgm.c           |  6 ++++--
 drivers/pwm/pwm-iqs620a.c             |  6 ++++--
 drivers/pwm/pwm-keembay.c             |  6 ++++--
 drivers/pwm/pwm-lpss.c                |  4 +++-
 drivers/pwm/pwm-meson.c               |  9 ++++-----
 drivers/pwm/pwm-mtk-disp.c            | 17 ++++++++---------
 drivers/pwm/pwm-pca9685.c             |  8 +++++---
 drivers/pwm/pwm-raspberrypi-poe.c     |  8 +++++---
 drivers/pwm/pwm-rockchip.c            | 12 +++++++-----
 drivers/pwm/pwm-sifive.c              |  4 +++-
 drivers/pwm/pwm-sl28cpld.c            |  8 +++++---
 drivers/pwm/pwm-sprd.c                | 13 ++++++-------
 drivers/pwm/pwm-stm32-lp.c            |  8 +++++---
 drivers/pwm/pwm-sun4i.c               | 13 ++++++++-----
 drivers/pwm/pwm-sunplus.c             |  6 ++++--
 drivers/pwm/pwm-visconti.c            |  4 +++-
 drivers/pwm/pwm-xilinx.c              |  8 +++++---
 include/linux/pwm.h                   |  4 ++--
 29 files changed, 145 insertions(+), 98 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index aa126ab80f0c..fa48825654c9 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -657,9 +657,10 @@ static void mvebu_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 	spin_unlock_irqrestore(&mvpwm->lock, flags);
 }
 
-static void mvebu_pwm_get_state(struct pwm_chip *chip,
-				struct pwm_device *pwm,
-				struct pwm_state *state) {
+static int mvebu_pwm_get_state(struct pwm_chip *chip,
+			       struct pwm_device *pwm,
+			       struct pwm_state *state)
+{
 
 	struct mvebu_pwm *mvpwm = to_mvebu_pwm(chip);
 	struct mvebu_gpio_chip *mvchip = mvpwm->mvchip;
@@ -693,6 +694,8 @@ static void mvebu_pwm_get_state(struct pwm_chip *chip,
 		state->enabled = false;
 
 	spin_unlock_irqrestore(&mvpwm->lock, flags);
+
+	return 0;
 }
 
 static int mvebu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index d6dd4d99a229..102c23f66ffd 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -1427,8 +1427,8 @@ static int ti_sn_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
-static void ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				struct pwm_state *state)
+static int ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
 {
 	struct ti_sn65dsi86 *pdata = pwm_chip_to_ti_sn_bridge(chip);
 	unsigned int pwm_en_inv;
@@ -1439,19 +1439,19 @@ static void ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	ret = regmap_read(pdata->regmap, SN_PWM_EN_INV_REG, &pwm_en_inv);
 	if (ret)
-		return;
+		return ret;
 
 	ret = ti_sn65dsi86_read_u16(pdata, SN_BACKLIGHT_SCALE_REG, &scale);
 	if (ret)
-		return;
+		return ret;
 
 	ret = ti_sn65dsi86_read_u16(pdata, SN_BACKLIGHT_REG, &backlight);
 	if (ret)
-		return;
+		return ret;
 
 	ret = regmap_read(pdata->regmap, SN_PWM_PRE_DIV_REG, &pre_div);
 	if (ret)
-		return;
+		return ret;
 
 	state->enabled = FIELD_GET(SN_PWM_EN_MASK, pwm_en_inv);
 	if (FIELD_GET(SN_PWM_INV_MASK, pwm_en_inv))
@@ -1466,6 +1466,8 @@ static void ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	if (state->duty_cycle > state->period)
 		state->duty_cycle = state->period;
+
+	return 0;
 }
 
 static const struct pwm_ops ti_sn_pwm_ops = {
diff --git a/drivers/leds/rgb/leds-qcom-lpg.c b/drivers/leds/rgb/leds-qcom-lpg.c
index 02f51cc61837..dc8f3a482a5a 100644
--- a/drivers/leds/rgb/leds-qcom-lpg.c
+++ b/drivers/leds/rgb/leds-qcom-lpg.c
@@ -968,7 +968,7 @@ static int lpg_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
-static void lpg_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+static int lpg_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 			      struct pwm_state *state)
 {
 	struct lpg *lpg = container_of(chip, struct lpg, pwm);
@@ -982,20 +982,20 @@ static void lpg_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	ret = regmap_read(lpg->map, chan->base + LPG_SIZE_CLK_REG, &val);
 	if (ret)
-		return;
+		return ret;
 
 	refclk = lpg_clk_rates[val & PWM_CLK_SELECT_MASK];
 	if (refclk) {
 		ret = regmap_read(lpg->map, chan->base + LPG_PREDIV_CLK_REG, &val);
 		if (ret)
-			return;
+			return ret;
 
 		pre_div = lpg_pre_divs[FIELD_GET(PWM_FREQ_PRE_DIV_MASK, val)];
 		m = FIELD_GET(PWM_FREQ_EXP_MASK, val);
 
 		ret = regmap_bulk_read(lpg->map, chan->base + PWM_VALUE_REG, &pwm_value, sizeof(pwm_value));
 		if (ret)
-			return;
+			return ret;
 
 		state->period = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * LPG_RESOLUTION * pre_div * (1 << m), refclk);
 		state->duty_cycle = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * pwm_value * pre_div * (1 << m), refclk);
@@ -1006,13 +1006,15 @@ static void lpg_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	ret = regmap_read(lpg->map, chan->base + PWM_ENABLE_CONTROL_REG, &val);
 	if (ret)
-		return;
+		return ret;
 
 	state->enabled = FIELD_GET(LPG_ENABLE_CONTROL_OUTPUT, val);
 	state->polarity = PWM_POLARITY_NORMAL;
 
 	if (state->duty_cycle > state->period)
 		state->duty_cycle = state->period;
+
+	return 0;
 }
 
 static const struct pwm_ops lpg_pwm_ops = {
diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 8e00a4286145..cdbc23649032 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -356,8 +356,8 @@ static int atmel_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				struct pwm_state *state)
+static int atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 	u32 sr, cmr;
@@ -396,6 +396,8 @@ static void atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 		state->polarity = PWM_POLARITY_INVERSED;
 	else
 		state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
 }
 
 static const struct pwm_ops atmel_pwm_ops = {
diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
index 7251037d4dd5..97ec131eb7c1 100644
--- a/drivers/pwm/pwm-bcm-iproc.c
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -68,8 +68,8 @@ static void iproc_pwmc_disable(struct iproc_pwmc *ip, unsigned int channel)
 	ndelay(400);
 }
 
-static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				 struct pwm_state *state)
+static int iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				struct pwm_state *state)
 {
 	struct iproc_pwmc *ip = to_iproc_pwmc(chip);
 	u64 tmp, multi, rate;
@@ -91,7 +91,7 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (rate == 0) {
 		state->period = 0;
 		state->duty_cycle = 0;
-		return;
+		return 0;
 	}
 
 	value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
@@ -107,6 +107,8 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
 	tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
 	state->duty_cycle = div64_u64(tmp, rate);
+
+	return 0;
 }
 
 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
index 7b357d1cf642..811e6f424927 100644
--- a/drivers/pwm/pwm-crc.c
+++ b/drivers/pwm/pwm-crc.c
@@ -121,8 +121,8 @@ static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-			      struct pwm_state *state)
+static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			     struct pwm_state *state)
 {
 	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
 	struct device *dev = crc_pwm->chip.dev;
@@ -132,13 +132,13 @@ static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg);
 	if (error) {
 		dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error);
-		return;
+		return -EIO;
 	}
 
 	error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg);
 	if (error) {
 		dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error);
-		return;
+		return -EIO;
 	}
 
 	clk_div = (clk_div_reg & ~PWM_OUTPUT_ENABLE) + 1;
@@ -149,6 +149,8 @@ static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 		DIV_ROUND_UP_ULL(duty_cycle_reg * state->period, PWM_MAX_LEVEL);
 	state->polarity = PWM_POLARITY_NORMAL;
 	state->enabled = !!(clk_div_reg & PWM_OUTPUT_ENABLE);
+
+	return 0;
 }
 
 static const struct pwm_ops crc_pwm_ops = {
diff --git a/drivers/pwm/pwm-cros-ec.c b/drivers/pwm/pwm-cros-ec.c
index 7f10f56c3eb6..0e5dbc5287e2 100644
--- a/drivers/pwm/pwm-cros-ec.c
+++ b/drivers/pwm/pwm-cros-ec.c
@@ -183,18 +183,16 @@ static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				  struct pwm_state *state)
+static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
 {
 	struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
 	struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
 	int ret;
 
 	ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm);
-	if (ret < 0) {
-		dev_err(chip->dev, "error getting initial duty: %d\n", ret);
-		return;
-	}
+	if (ret < 0)
+		return ret;
 
 	state->enabled = (ret > 0);
 	state->period = EC_PWM_MAX_DUTY;
@@ -212,6 +210,8 @@ static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 		state->duty_cycle = channel->duty_cycle;
 	else
 		state->duty_cycle = ret;
+
+	return 0;
 }
 
 static struct pwm_device *
diff --git a/drivers/pwm/pwm-dwc.c b/drivers/pwm/pwm-dwc.c
index 7568300bb11e..bd2308812096 100644
--- a/drivers/pwm/pwm-dwc.c
+++ b/drivers/pwm/pwm-dwc.c
@@ -163,8 +163,8 @@ static int dwc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-			      struct pwm_state *state)
+static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			     struct pwm_state *state)
 {
 	struct dwc_pwm *dwc = to_dwc_pwm(chip);
 	u64 duty, period;
@@ -188,6 +188,8 @@ static void dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->polarity = PWM_POLARITY_INVERSED;
 
 	pm_runtime_put_sync(chip->dev);
+
+	return 0;
 }
 
 static const struct pwm_ops dwc_pwm_ops = {
diff --git a/drivers/pwm/pwm-hibvt.c b/drivers/pwm/pwm-hibvt.c
index 333f1b18ff4e..12c05c155cab 100644
--- a/drivers/pwm/pwm-hibvt.c
+++ b/drivers/pwm/pwm-hibvt.c
@@ -128,8 +128,8 @@ static void hibvt_pwm_set_polarity(struct pwm_chip *chip,
 				PWM_POLARITY_MASK, (0x0 << PWM_POLARITY_SHIFT));
 }
 
-static void hibvt_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				struct pwm_state *state)
+static int hibvt_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
 {
 	struct hibvt_pwm_chip *hi_pwm_chip = to_hibvt_pwm_chip(chip);
 	void __iomem *base;
@@ -146,6 +146,8 @@ static void hibvt_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	value = readl(base + PWM_CTRL_ADDR(pwm->hwpwm));
 	state->enabled = (PWM_ENABLE_MASK & value);
+
+	return 0;
 }
 
 static int hibvt_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
index e5e7b7c339a8..ed1aad96fff0 100644
--- a/drivers/pwm/pwm-imx-tpm.c
+++ b/drivers/pwm/pwm-imx-tpm.c
@@ -132,9 +132,9 @@ static int pwm_imx_tpm_round_state(struct pwm_chip *chip,
 	return 0;
 }
 
-static void pwm_imx_tpm_get_state(struct pwm_chip *chip,
-				  struct pwm_device *pwm,
-				  struct pwm_state *state)
+static int pwm_imx_tpm_get_state(struct pwm_chip *chip,
+				 struct pwm_device *pwm,
+				 struct pwm_state *state)
 {
 	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
 	u32 rate, val, prescale;
@@ -164,6 +164,8 @@ static void pwm_imx_tpm_get_state(struct pwm_chip *chip,
 
 	/* get channel status */
 	state->enabled = FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val) ? true : false;
+
+	return 0;
 }
 
 /* this function is supposed to be called with mutex hold */
diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
index ea91a2f81a9f..29a3089c534c 100644
--- a/drivers/pwm/pwm-imx27.c
+++ b/drivers/pwm/pwm-imx27.c
@@ -118,8 +118,8 @@ static void pwm_imx27_clk_disable_unprepare(struct pwm_imx27_chip *imx)
 	clk_disable_unprepare(imx->clk_ipg);
 }
 
-static void pwm_imx27_get_state(struct pwm_chip *chip,
-				struct pwm_device *pwm, struct pwm_state *state)
+static int pwm_imx27_get_state(struct pwm_chip *chip,
+			       struct pwm_device *pwm, struct pwm_state *state)
 {
 	struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
 	u32 period, prescaler, pwm_clk, val;
@@ -128,7 +128,7 @@ static void pwm_imx27_get_state(struct pwm_chip *chip,
 
 	ret = pwm_imx27_clk_prepare_enable(imx);
 	if (ret < 0)
-		return;
+		return ret;
 
 	val = readl(imx->mmio_base + MX3_PWMCR);
 
@@ -170,6 +170,8 @@ static void pwm_imx27_get_state(struct pwm_chip *chip,
 	state->duty_cycle = DIV_ROUND_UP_ULL(tmp, pwm_clk);
 
 	pwm_imx27_clk_disable_unprepare(imx);
+
+	return 0;
 }
 
 static void pwm_imx27_sw_reset(struct pwm_chip *chip)
diff --git a/drivers/pwm/pwm-intel-lgm.c b/drivers/pwm/pwm-intel-lgm.c
index b66c35074087..0cd7dd548e82 100644
--- a/drivers/pwm/pwm-intel-lgm.c
+++ b/drivers/pwm/pwm-intel-lgm.c
@@ -86,8 +86,8 @@ static int lgm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return lgm_pwm_enable(chip, 1);
 }
 
-static void lgm_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-			      struct pwm_state *state)
+static int lgm_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			     struct pwm_state *state)
 {
 	struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
 	u32 duty, val;
@@ -100,6 +100,8 @@ static void lgm_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	regmap_read(pc->regmap, LGM_PWM_FAN_CON0, &val);
 	duty = FIELD_GET(LGM_PWM_FAN_DC_MSK, val);
 	state->duty_cycle = DIV_ROUND_UP(duty * pc->period, LGM_PWM_MAX_DUTY_CYCLE);
+
+	return 0;
 }
 
 static const struct pwm_ops lgm_pwm_ops = {
diff --git a/drivers/pwm/pwm-iqs620a.c b/drivers/pwm/pwm-iqs620a.c
index 54bd95a5cab0..15aae53db5ab 100644
--- a/drivers/pwm/pwm-iqs620a.c
+++ b/drivers/pwm/pwm-iqs620a.c
@@ -104,8 +104,8 @@ static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
-static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				 struct pwm_state *state)
+static int iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				struct pwm_state *state)
 {
 	struct iqs620_pwm_private *iqs620_pwm;
 
@@ -126,6 +126,8 @@ static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	mutex_unlock(&iqs620_pwm->lock);
 
 	state->period = IQS620_PWM_PERIOD_NS;
+
+	return 0;
 }
 
 static int iqs620_pwm_notifier(struct notifier_block *notifier,
diff --git a/drivers/pwm/pwm-keembay.c b/drivers/pwm/pwm-keembay.c
index 733811b05721..ac02d8bb4a0b 100644
--- a/drivers/pwm/pwm-keembay.c
+++ b/drivers/pwm/pwm-keembay.c
@@ -89,8 +89,8 @@ static void keembay_pwm_disable(struct keembay_pwm *priv, int ch)
 				KMB_PWM_LEADIN_OFFSET(ch));
 }
 
-static void keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				  struct pwm_state *state)
+static int keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
 {
 	struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
 	unsigned long long high, low;
@@ -113,6 +113,8 @@ static void keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->duty_cycle = DIV_ROUND_UP_ULL(high, clk_rate);
 	state->period = DIV_ROUND_UP_ULL(high + low, clk_rate);
 	state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
 }
 
 static int keembay_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 36d4e83e6b79..7c3c2e0f0bf4 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -168,7 +168,7 @@ static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
-static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+static int pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 			       struct pwm_state *state)
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
@@ -199,6 +199,8 @@ static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->enabled = !!(ctrl & PWM_ENABLE);
 
 	pm_runtime_put(chip->dev);
+
+	return 0;
 }
 
 static const struct pwm_ops pwm_lpss_ops = {
diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 57112f438c6d..6bca7c0bf65f 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -318,17 +318,14 @@ static unsigned int meson_pwm_cnt_to_ns(struct pwm_chip *chip,
 	return cnt * fin_ns * (channel->pre_div + 1);
 }
 
-static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				struct pwm_state *state)
+static int meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
 {
 	struct meson_pwm *meson = to_meson_pwm(chip);
 	struct meson_pwm_channel_data *channel_data;
 	struct meson_pwm_channel *channel;
 	u32 value, tmp;
 
-	if (!state)
-		return;
-
 	channel = &meson->channels[pwm->hwpwm];
 	channel_data = &meson_pwm_per_channel_data[pwm->hwpwm];
 
@@ -357,6 +354,8 @@ static void meson_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 		state->period = 0;
 		state->duty_cycle = 0;
 	}
+
+	return 0;
 }
 
 static const struct pwm_ops meson_pwm_ops = {
diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
index c605013e4114..ce601f5ac9a6 100644
--- a/drivers/pwm/pwm-mtk-disp.c
+++ b/drivers/pwm/pwm-mtk-disp.c
@@ -172,9 +172,9 @@ static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void mtk_disp_pwm_get_state(struct pwm_chip *chip,
-				   struct pwm_device *pwm,
-				   struct pwm_state *state)
+static int mtk_disp_pwm_get_state(struct pwm_chip *chip,
+				  struct pwm_device *pwm,
+				  struct pwm_state *state)
 {
 	struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
 	u64 rate, period, high_width;
@@ -182,16 +182,13 @@ static void mtk_disp_pwm_get_state(struct pwm_chip *chip,
 	int err;
 
 	err = clk_prepare_enable(mdp->clk_main);
-	if (err < 0) {
-		dev_err(chip->dev, "Can't enable mdp->clk_main: %pe\n", ERR_PTR(err));
-		return;
-	}
+	if (err < 0)
+		return err;
 
 	err = clk_prepare_enable(mdp->clk_mm);
 	if (err < 0) {
-		dev_err(chip->dev, "Can't enable mdp->clk_mm: %pe\n", ERR_PTR(err));
 		clk_disable_unprepare(mdp->clk_main);
-		return;
+		return err;
 	}
 
 	rate = clk_get_rate(mdp->clk_main);
@@ -211,6 +208,8 @@ static void mtk_disp_pwm_get_state(struct pwm_chip *chip,
 	state->polarity = PWM_POLARITY_NORMAL;
 	clk_disable_unprepare(mdp->clk_mm);
 	clk_disable_unprepare(mdp->clk_main);
+
+	return 0;
 }
 
 static const struct pwm_ops mtk_disp_pwm_ops = {
diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index c91fa7f9e33d..9353938b24c2 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -431,8 +431,8 @@ static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
-static void pca9685_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				  struct pwm_state *state)
+static int pca9685_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
 {
 	struct pca9685 *pca = to_pca(chip);
 	unsigned long long duty;
@@ -458,12 +458,14 @@ static void pca9685_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 		 */
 		state->duty_cycle = 0;
 		state->enabled = false;
-		return;
+		return 0;
 	}
 
 	state->enabled = true;
 	duty = pca9685_pwm_get_duty(pca, pwm->hwpwm);
 	state->duty_cycle = DIV_ROUND_DOWN_ULL(duty * state->period, PCA9685_COUNTER_RANGE);
+
+	return 0;
 }
 
 static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
diff --git a/drivers/pwm/pwm-raspberrypi-poe.c b/drivers/pwm/pwm-raspberrypi-poe.c
index 6ff73029f367..2939b71a7ba7 100644
--- a/drivers/pwm/pwm-raspberrypi-poe.c
+++ b/drivers/pwm/pwm-raspberrypi-poe.c
@@ -82,9 +82,9 @@ static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware,
 	return 0;
 }
 
-static void raspberrypi_pwm_get_state(struct pwm_chip *chip,
-				      struct pwm_device *pwm,
-				      struct pwm_state *state)
+static int raspberrypi_pwm_get_state(struct pwm_chip *chip,
+				     struct pwm_device *pwm,
+				     struct pwm_state *state)
 {
 	struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);
 
@@ -93,6 +93,8 @@ static void raspberrypi_pwm_get_state(struct pwm_chip *chip,
 					 RPI_PWM_MAX_DUTY);
 	state->enabled = !!(rpipwm->duty_cycle);
 	state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
 }
 
 static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index f3647b317152..004807201ffe 100644
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -57,9 +57,9 @@ static inline struct rockchip_pwm_chip *to_rockchip_pwm_chip(struct pwm_chip *c)
 	return container_of(c, struct rockchip_pwm_chip, chip);
 }
 
-static void rockchip_pwm_get_state(struct pwm_chip *chip,
-				   struct pwm_device *pwm,
-				   struct pwm_state *state)
+static int rockchip_pwm_get_state(struct pwm_chip *chip,
+				  struct pwm_device *pwm,
+				  struct pwm_state *state)
 {
 	struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
 	u32 enable_conf = pc->data->enable_conf;
@@ -70,11 +70,11 @@ static void rockchip_pwm_get_state(struct pwm_chip *chip,
 
 	ret = clk_enable(pc->pclk);
 	if (ret)
-		return;
+		return ret;
 
 	ret = clk_enable(pc->clk);
 	if (ret)
-		return;
+		return ret;
 
 	clk_rate = clk_get_rate(pc->clk);
 
@@ -96,6 +96,8 @@ static void rockchip_pwm_get_state(struct pwm_chip *chip,
 
 	clk_disable(pc->clk);
 	clk_disable(pc->pclk);
+
+	return 0;
 }
 
 static void rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index 2d4fa5e5fdd4..0056d642cc83 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -105,7 +105,7 @@ static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata,
 		"New real_period = %u ns\n", ddata->real_period);
 }
 
-static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 				 struct pwm_state *state)
 {
 	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
@@ -123,6 +123,8 @@ static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->duty_cycle =
 		(u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
 	state->polarity = PWM_POLARITY_INVERSED;
+
+	return 0;
 }
 
 static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-sl28cpld.c b/drivers/pwm/pwm-sl28cpld.c
index 589aeaaa6ac8..e64900ad4ba1 100644
--- a/drivers/pwm/pwm-sl28cpld.c
+++ b/drivers/pwm/pwm-sl28cpld.c
@@ -87,9 +87,9 @@ struct sl28cpld_pwm {
 #define sl28cpld_pwm_from_chip(_chip) \
 	container_of(_chip, struct sl28cpld_pwm, pwm_chip)
 
-static void sl28cpld_pwm_get_state(struct pwm_chip *chip,
-				   struct pwm_device *pwm,
-				   struct pwm_state *state)
+static int sl28cpld_pwm_get_state(struct pwm_chip *chip,
+				  struct pwm_device *pwm,
+				  struct pwm_state *state)
 {
 	struct sl28cpld_pwm *priv = sl28cpld_pwm_from_chip(chip);
 	unsigned int reg;
@@ -115,6 +115,8 @@ static void sl28cpld_pwm_get_state(struct pwm_chip *chip,
 	 * the PWM core.
 	 */
 	state->duty_cycle = min(state->duty_cycle, state->period);
+
+	return 0;
 }
 
 static int sl28cpld_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-sprd.c b/drivers/pwm/pwm-sprd.c
index 7004f55bbf11..aa06b3ce81a6 100644
--- a/drivers/pwm/pwm-sprd.c
+++ b/drivers/pwm/pwm-sprd.c
@@ -65,8 +65,8 @@ static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid,
 	writel_relaxed(val, spc->base + offset);
 }
 
-static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-			       struct pwm_state *state)
+static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			      struct pwm_state *state)
 {
 	struct sprd_pwm_chip *spc =
 		container_of(chip, struct sprd_pwm_chip, chip);
@@ -80,11 +80,8 @@ static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * reading to the registers.
 	 */
 	ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
-	if (ret) {
-		dev_err(spc->dev, "failed to enable pwm%u clocks\n",
-			pwm->hwpwm);
-		return;
-	}
+	if (ret)
+		return ret;
 
 	val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_ENABLE);
 	if (val & SPRD_PWM_ENABLE_BIT)
@@ -113,6 +110,8 @@ static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	/* Disable PWM clocks if the PWM channel is not in enable state. */
 	if (!state->enabled)
 		clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
+
+	return 0;
 }
 
 static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
diff --git a/drivers/pwm/pwm-stm32-lp.c b/drivers/pwm/pwm-stm32-lp.c
index 3115abb3f52a..39364c52cfe4 100644
--- a/drivers/pwm/pwm-stm32-lp.c
+++ b/drivers/pwm/pwm-stm32-lp.c
@@ -157,9 +157,9 @@ static int stm32_pwm_lp_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return ret;
 }
 
-static void stm32_pwm_lp_get_state(struct pwm_chip *chip,
-				   struct pwm_device *pwm,
-				   struct pwm_state *state)
+static int stm32_pwm_lp_get_state(struct pwm_chip *chip,
+				  struct pwm_device *pwm,
+				  struct pwm_state *state)
 {
 	struct stm32_pwm_lp *priv = to_stm32_pwm_lp(chip);
 	unsigned long rate = clk_get_rate(priv->clk);
@@ -185,6 +185,8 @@ static void stm32_pwm_lp_get_state(struct pwm_chip *chip,
 	tmp = prd - val;
 	tmp = (tmp << presc) * NSEC_PER_SEC;
 	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate);
+
+	return 0;
 }
 
 static const struct pwm_ops stm32_pwm_lp_ops = {
diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index c8445b0a3339..ead909400e64 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -108,9 +108,9 @@ static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
 	writel(val, chip->base + offset);
 }
 
-static void sun4i_pwm_get_state(struct pwm_chip *chip,
-				struct pwm_device *pwm,
-				struct pwm_state *state)
+static int sun4i_pwm_get_state(struct pwm_chip *chip,
+			       struct pwm_device *pwm,
+			       struct pwm_state *state)
 {
 	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 	u64 clk_rate, tmp;
@@ -132,7 +132,7 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
 		state->duty_cycle = DIV_ROUND_UP_ULL(state->period, 2);
 		state->polarity = PWM_POLARITY_NORMAL;
 		state->enabled = true;
-		return;
+		return 0;
 	}
 
 	if ((PWM_REG_PRESCAL(val, pwm->hwpwm) == PWM_PRESCAL_MASK) &&
@@ -142,7 +142,8 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
 		prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];
 
 	if (prescaler == 0)
-		return;
+		/* huh? is this an error? */
+		return 0;
 
 	if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
 		state->polarity = PWM_POLARITY_NORMAL;
@@ -162,6 +163,8 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
 
 	tmp = (u64)prescaler * NSEC_PER_SEC * PWM_REG_PRD(val);
 	state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
+
+	return 0;
 }
 
 static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
diff --git a/drivers/pwm/pwm-sunplus.c b/drivers/pwm/pwm-sunplus.c
index e776fd16512d..d6ebe9f03b35 100644
--- a/drivers/pwm/pwm-sunplus.c
+++ b/drivers/pwm/pwm-sunplus.c
@@ -124,8 +124,8 @@ static int sunplus_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void sunplus_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				  struct pwm_state *state)
+static int sunplus_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
 {
 	struct sunplus_pwm *priv = to_sunplus_pwm(chip);
 	u32 mode0, dd_freq, duty;
@@ -155,6 +155,8 @@ static void sunplus_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 	state->polarity = PWM_POLARITY_NORMAL;
+
+	return 0;
 }
 
 static const struct pwm_ops sunplus_pwm_ops = {
diff --git a/drivers/pwm/pwm-visconti.c b/drivers/pwm/pwm-visconti.c
index 927c4cbb1daf..d78a47cdd139 100644
--- a/drivers/pwm/pwm-visconti.c
+++ b/drivers/pwm/pwm-visconti.c
@@ -103,7 +103,7 @@ static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
-static void visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+static int visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 				   struct pwm_state *state)
 {
 	struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
@@ -122,6 +122,8 @@ static void visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm
 		state->polarity = PWM_POLARITY_NORMAL;
 
 	state->enabled = true;
+
+	return 0;
 }
 
 static const struct pwm_ops visconti_pwm_ops = {
diff --git a/drivers/pwm/pwm-xilinx.c b/drivers/pwm/pwm-xilinx.c
index 4dab2b86c427..f7a50fdcd9a5 100644
--- a/drivers/pwm/pwm-xilinx.c
+++ b/drivers/pwm/pwm-xilinx.c
@@ -169,9 +169,9 @@ static int xilinx_pwm_apply(struct pwm_chip *chip, struct pwm_device *unused,
 	return 0;
 }
 
-static void xilinx_pwm_get_state(struct pwm_chip *chip,
-				 struct pwm_device *unused,
-				 struct pwm_state *state)
+static int xilinx_pwm_get_state(struct pwm_chip *chip,
+				struct pwm_device *unused,
+				struct pwm_state *state)
 {
 	struct xilinx_timer_priv *priv = xilinx_pwm_chip_to_priv(chip);
 	u32 tlr0, tlr1, tcsr0, tcsr1;
@@ -191,6 +191,8 @@ static void xilinx_pwm_get_state(struct pwm_chip *chip,
 	 */
 	if (state->period == state->duty_cycle)
 		state->duty_cycle = 0;
+
+	return 0;
 }
 
 static const struct pwm_ops xilinx_pwm_ops = {
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 9429930c5566..ee17e92ac6c0 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -276,8 +276,8 @@ struct pwm_ops {
 		       struct pwm_capture *result, unsigned long timeout);
 	int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
 		     const struct pwm_state *state);
-	void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
-			  struct pwm_state *state);
+	int (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
+			 struct pwm_state *state);
 	struct module *owner;
 };
 
-- 
2.37.2

[PATCH 2/3] pwm/tracing: Also record trace events for failed apply calls

[Uwe Kleine-König]

Record and report an error code for the events. This allows to report
about failed calls without ambiguity and so gives a more complete
picture.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/core.c         | 18 ++++++++----------
 include/trace/events/pwm.h | 20 ++++++++++----------
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 0e042410f6b9..381db04cfa00 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -108,8 +108,8 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	}
 
 	if (pwm->chip->ops->get_state) {
-		pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
-		trace_pwm_get(pwm, &pwm->state);
+		err = pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
+		trace_pwm_get(pwm, &pwm->state, err);
 
 		if (IS_ENABLED(CONFIG_PWM_DEBUG))
 			pwm->last = pwm->state;
@@ -457,8 +457,8 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 	 * checks.
 	 */
 
-	chip->ops->get_state(chip, pwm, &s1);
-	trace_pwm_get(pwm, &s1);
+	err = chip->ops->get_state(chip, pwm, &s1);
+	trace_pwm_get(pwm, &s1, err);
 
 	/*
 	 * The lowlevel driver either ignored .polarity (which is a bug) or as
@@ -514,16 +514,15 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 
 	/* reapply the state that the driver reported being configured. */
 	err = chip->ops->apply(chip, pwm, &s1);
+	trace_pwm_apply(pwm, &s1, err);
 	if (err) {
 		*last = s1;
 		dev_err(chip->dev, "failed to reapply current setting\n");
 		return;
 	}
 
-	trace_pwm_apply(pwm, &s1);
-
-	chip->ops->get_state(chip, pwm, last);
-	trace_pwm_get(pwm, last);
+	err = chip->ops->get_state(chip, pwm, last);
+	trace_pwm_get(pwm, last, err);
 
 	/* reapplication of the current state should give an exact match */
 	if (s1.enabled != last->enabled ||
@@ -571,11 +570,10 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
 		return 0;
 
 	err = chip->ops->apply(chip, pwm, state);
+	trace_pwm_apply(pwm, state, err);
 	if (err)
 		return err;
 
-	trace_pwm_apply(pwm, state);
-
 	pwm->state = *state;
 
 	/*
diff --git a/include/trace/events/pwm.h b/include/trace/events/pwm.h
index cf243de41cc8..12b35e4ff917 100644
--- a/include/trace/events/pwm.h
+++ b/include/trace/events/pwm.h
@@ -10,9 +10,9 @@
 
 DECLARE_EVENT_CLASS(pwm,
 
-	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state),
+	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state, int err),
 
-	TP_ARGS(pwm, state),
+	TP_ARGS(pwm, state, err),
 
 	TP_STRUCT__entry(
 		__field(struct pwm_device *, pwm)
@@ -20,6 +20,7 @@ DECLARE_EVENT_CLASS(pwm,
 		__field(u64, duty_cycle)
 		__field(enum pwm_polarity, polarity)
 		__field(bool, enabled)
+		__field(int, err)
 	),
 
 	TP_fast_assign(
@@ -28,28 +29,27 @@ DECLARE_EVENT_CLASS(pwm,
 		__entry->duty_cycle = state->duty_cycle;
 		__entry->polarity = state->polarity;
 		__entry->enabled = state->enabled;
+		__entry->err = err;
 	),
 
-	TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d",
+	TP_printk("%p: period=%llu duty_cycle=%llu polarity=%d enabled=%d err=%d",
 		  __entry->pwm, __entry->period, __entry->duty_cycle,
-		  __entry->polarity, __entry->enabled)
+		  __entry->polarity, __entry->enabled, __entry->err)
 
 );
 
 DEFINE_EVENT(pwm, pwm_apply,
 
-	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state),
-
-	TP_ARGS(pwm, state)
+	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state, int err),
 
+	TP_ARGS(pwm, state, err)
 );
 
 DEFINE_EVENT(pwm, pwm_get,
 
-	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state),
-
-	TP_ARGS(pwm, state)
+	TP_PROTO(struct pwm_device *pwm, const struct pwm_state *state, int err),
 
+	TP_ARGS(pwm, state, err)
 );
 
 #endif /* _TRACE_PWM_H */
-- 
2.37.2

[PATCH 3/3] pwm: Handle .get_state() failures

[Uwe Kleine-König]

This suppresses diagnosis for PWM_DEBUG routines and makes sure that
pwm->state isn't modified in pwm_device_request() if .get_state() fails.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/pwm/core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 381db04cfa00..421573590613 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -108,9 +108,14 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	}
 
 	if (pwm->chip->ops->get_state) {
-		err = pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
+		struct pwm_state state;
+
+		err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
 		trace_pwm_get(pwm, &pwm->state, err);
 
+		if (!err)
+			pwm->state = state;
+
 		if (IS_ENABLED(CONFIG_PWM_DEBUG))
 			pwm->last = pwm->state;
 	}
@@ -459,6 +464,9 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 
 	err = chip->ops->get_state(chip, pwm, &s1);
 	trace_pwm_get(pwm, &s1, err);
+	if (err)
+		/* If that failed there isn't much to debug */
+		return;
 
 	/*
 	 * The lowlevel driver either ignored .polarity (which is a bug) or as
@@ -523,6 +531,8 @@ static void pwm_apply_state_debug(struct pwm_device *pwm,
 
 	err = chip->ops->get_state(chip, pwm, last);
 	trace_pwm_get(pwm, last, err);
+	if (err)
+		return;
 
 	/* reapplication of the current state should give an exact match */
 	if (s1.enabled != last->enabled ||
-- 
2.37.2

Re: [PATCH 1/3] pwm: Change prototype of .get_state() callback to return an error

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 4232 bytes --]

On Fri, Sep 16, 2022 at 05:15:04PM +0200, Uwe Kleine-König wrote:
[...]
> diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
> index 7b357d1cf642..811e6f424927 100644
> --- a/drivers/pwm/pwm-crc.c
> +++ b/drivers/pwm/pwm-crc.c
> @@ -121,8 +121,8 @@ static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  	return 0;
>  }
>  
> -static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> -			      struct pwm_state *state)
> +static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> +			     struct pwm_state *state)
>  {
>  	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
>  	struct device *dev = crc_pwm->chip.dev;
> @@ -132,13 +132,13 @@ static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  	error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg);
>  	if (error) {
>  		dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error);
> -		return;
> +		return -EIO;
>  	}
>  
>  	error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg);
>  	if (error) {
>  		dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error);
> -		return;
> +		return -EIO;
>  	}

In other drivers you propagate errors from regmap_read(), why not here?

> diff --git a/drivers/pwm/pwm-sprd.c b/drivers/pwm/pwm-sprd.c
> index 7004f55bbf11..aa06b3ce81a6 100644
> --- a/drivers/pwm/pwm-sprd.c
> +++ b/drivers/pwm/pwm-sprd.c
> @@ -65,8 +65,8 @@ static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid,
>  	writel_relaxed(val, spc->base + offset);
>  }
>  
> -static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> -			       struct pwm_state *state)
> +static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> +			      struct pwm_state *state)
>  {
>  	struct sprd_pwm_chip *spc =
>  		container_of(chip, struct sprd_pwm_chip, chip);
> @@ -80,11 +80,8 @@ static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  	 * reading to the registers.
>  	 */
>  	ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
> -	if (ret) {
> -		dev_err(spc->dev, "failed to enable pwm%u clocks\n",
> -			pwm->hwpwm);

This might be useful information, so perhaps leave it in?

[...]
> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> index c8445b0a3339..ead909400e64 100644
> --- a/drivers/pwm/pwm-sun4i.c
> +++ b/drivers/pwm/pwm-sun4i.c
> @@ -108,9 +108,9 @@ static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
>  	writel(val, chip->base + offset);
>  }
>  
> -static void sun4i_pwm_get_state(struct pwm_chip *chip,
> -				struct pwm_device *pwm,
> -				struct pwm_state *state)
> +static int sun4i_pwm_get_state(struct pwm_chip *chip,
> +			       struct pwm_device *pwm,
> +			       struct pwm_state *state)
>  {
>  	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
>  	u64 clk_rate, tmp;
> @@ -132,7 +132,7 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
>  		state->duty_cycle = DIV_ROUND_UP_ULL(state->period, 2);
>  		state->polarity = PWM_POLARITY_NORMAL;
>  		state->enabled = true;
> -		return;
> +		return 0;
>  	}
>  
>  	if ((PWM_REG_PRESCAL(val, pwm->hwpwm) == PWM_PRESCAL_MASK) &&
> @@ -142,7 +142,8 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
>  		prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];
>  
>  	if (prescaler == 0)
> -		return;
> +		/* huh? is this an error? */
> +		return 0;

Yeah, I think this would count as an error. The prescaler value returned
from that table is 0 in what seems to be "invalid" configurations. If
you look at how this is used in sun4i_pwm_calculate(), these entries are
skipped for the computation of the duty cycle. So I would expect this to
happen in either an invalidly configured or completely unconfigured PWM.

That raises the question about what to do in these cases. If we return
an error, that could potentially throw off consumers. So perhaps the
closest would be to return a disabled PWM? Or perhaps it'd be up to the
consumer to provide some fallback configuration for invalidly configured
or unconfigured PWMs.

Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH 2/3] pwm/tracing: Also record trace events for failed apply calls

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 569 bytes --]

On Fri, Sep 16, 2022 at 05:15:05PM +0200, Uwe Kleine-König wrote:
> Record and report an error code for the events. This allows to report
> about failed calls without ambiguity and so gives a more complete
> picture.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/pwm/core.c         | 18 ++++++++----------
>  include/trace/events/pwm.h | 20 ++++++++++----------
>  2 files changed, 18 insertions(+), 20 deletions(-)

Yeah, I like this one. Should make the traces much more useful in the
failure cases.

Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH 3/3] pwm: Handle .get_state() failures

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1392 bytes --]

On Fri, Sep 16, 2022 at 05:15:06PM +0200, Uwe Kleine-König wrote:
> This suppresses diagnosis for PWM_DEBUG routines and makes sure that
> pwm->state isn't modified in pwm_device_request() if .get_state() fails.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/pwm/core.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index 381db04cfa00..421573590613 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -108,9 +108,14 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
>  	}
>  
>  	if (pwm->chip->ops->get_state) {
> -		err = pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
> +		struct pwm_state state;
> +
> +		err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);
>  		trace_pwm_get(pwm, &pwm->state, err);
>  
> +		if (!err)
> +			pwm->state = state;

So basically this means that callers of pwm_get_state() will get the
zeroed out pwm->state. This can cause issues with the likes of
pwm_set_relative_duty_cycle() which many drivers would use. Do we
perhaps want to set an internal error in this case so that it can be
propagated to callers in pwm_get_state()? That would allow them to fall
back to some default configuration rather than potentially breaking
altogether.

Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]

Re: [PATCH 1/3] pwm: Change prototype of .get_state() callback to return an error

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 5261 bytes --]

On Wed, Sep 28, 2022 at 02:49:00PM +0200, Thierry Reding wrote:
> On Fri, Sep 16, 2022 at 05:15:04PM +0200, Uwe Kleine-König wrote:
> [...]
> > diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
> > index 7b357d1cf642..811e6f424927 100644
> > --- a/drivers/pwm/pwm-crc.c
> > +++ b/drivers/pwm/pwm-crc.c
> > @@ -121,8 +121,8 @@ static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> >  	return 0;
> >  }
> >  
> > -static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > -			      struct pwm_state *state)
> > +static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > +			     struct pwm_state *state)
> >  {
> >  	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
> >  	struct device *dev = crc_pwm->chip.dev;
> > @@ -132,13 +132,13 @@ static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> >  	error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg);
> >  	if (error) {
> >  		dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error);
> > -		return;
> > +		return -EIO;
> >  	}
> >  
> >  	error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg);
> >  	if (error) {
> >  		dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error);
> > -		return;
> > +		return -EIO;
> >  	}
> 
> In other drivers you propagate errors from regmap_read(), why not here?

Oh, this is indeed wrong and should be "return error".

> 
> > diff --git a/drivers/pwm/pwm-sprd.c b/drivers/pwm/pwm-sprd.c
> > index 7004f55bbf11..aa06b3ce81a6 100644
> > --- a/drivers/pwm/pwm-sprd.c
> > +++ b/drivers/pwm/pwm-sprd.c
> > @@ -65,8 +65,8 @@ static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid,
> >  	writel_relaxed(val, spc->base + offset);
> >  }
> >  
> > -static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > -			       struct pwm_state *state)
> > +static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > +			      struct pwm_state *state)
> >  {
> >  	struct sprd_pwm_chip *spc =
> >  		container_of(chip, struct sprd_pwm_chip, chip);
> > @@ -80,11 +80,8 @@ static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> >  	 * reading to the registers.
> >  	 */
> >  	ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
> > -	if (ret) {
> > -		dev_err(spc->dev, "failed to enable pwm%u clocks\n",
> > -			pwm->hwpwm);
> 
> This might be useful information, so perhaps leave it in?

Ok, I don't like .get_state emitting an error, but agreed, that's an
orthogonal issue that shouldn't be addressed en passant in this change.

> [...]
> > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> > index c8445b0a3339..ead909400e64 100644
> > --- a/drivers/pwm/pwm-sun4i.c
> > +++ b/drivers/pwm/pwm-sun4i.c
> > @@ -108,9 +108,9 @@ static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
> >  	writel(val, chip->base + offset);
> >  }
> >  
> > -static void sun4i_pwm_get_state(struct pwm_chip *chip,
> > -				struct pwm_device *pwm,
> > -				struct pwm_state *state)
> > +static int sun4i_pwm_get_state(struct pwm_chip *chip,
> > +			       struct pwm_device *pwm,
> > +			       struct pwm_state *state)
> >  {
> >  	struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
> >  	u64 clk_rate, tmp;
> > @@ -132,7 +132,7 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
> >  		state->duty_cycle = DIV_ROUND_UP_ULL(state->period, 2);
> >  		state->polarity = PWM_POLARITY_NORMAL;
> >  		state->enabled = true;
> > -		return;
> > +		return 0;
> >  	}
> >  
> >  	if ((PWM_REG_PRESCAL(val, pwm->hwpwm) == PWM_PRESCAL_MASK) &&
> > @@ -142,7 +142,8 @@ static void sun4i_pwm_get_state(struct pwm_chip *chip,
> >  		prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];
> >  
> >  	if (prescaler == 0)
> > -		return;
> > +		/* huh? is this an error? */
> > +		return 0;
> 
> Yeah, I think this would count as an error. The prescaler value returned
> from that table is 0 in what seems to be "invalid" configurations. If
> you look at how this is used in sun4i_pwm_calculate(), these entries are
> skipped for the computation of the duty cycle. So I would expect this to
> happen in either an invalidly configured or completely unconfigured PWM.
> 
> That raises the question about what to do in these cases. If we return
> an error, that could potentially throw off consumers. So perhaps the
> closest would be to return a disabled PWM? Or perhaps it'd be up to the
> consumer to provide some fallback configuration for invalidly configured
> or unconfigured PWMs.

This is something I'd address on the framework level. i.e. don't care in
the lowlevel driver about setting .enabled = false (or whatever we
choose to do) but care for that in drivers/pwm/core.c.

Note that the status quo is that if that error happens the consumer sees
whatever state the lowlevel driver stored in pwm->state, without an
error indication.

Will send a v2.

Best regards
Uwe

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]