Merge tag 'pwm/for-6.17-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux

Pull pwm fixes from Uwe Kleine-König:
 "Two fixes for the mediatek and the imx-tpm driver. Both are old
  (v4.12-rc1 and v5.2-rc1 respectively).

  The mediatek issue is that both period and duty_cycle were configured
  to higher values than requested. For most applications the period part
  is no tragedy, but a PWM that is configured for duty_cycle = 0 should
  really emit a constant inactive signal. That was noticed by an LED not
  being completely off in this case (two commits for one fix: a
  preparatory one and the actual fix in the second one).

  For the imx-tpm PWM driver the fixed issue is that the first period is
  quite a bit too long under some circumstances. So it might take up to
  UINT32_MAX << 7 clock ticks until the PWM starts toggling. With an
  assumed input clock rate of 166 MHz (completely made up) that's 55
  minutes"

* tag 'pwm/for-6.17-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ukleinek/linux:
  pwm: imx-tpm: Reset counter if CMOD is 0
  pwm: mediatek: Fix duty and period setting
  pwm: mediatek: Handle hardware enable and clock enable separately

2 files changed, 46 insertions, 34 deletions

diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
index 7ee7b65b9b90..5b399de16d60 100644
--- a/drivers/pwm/pwm-imx-tpm.c
+++ b/drivers/pwm/pwm-imx-tpm.c
@@ -205,6 +205,15 @@ static int pwm_imx_tpm_apply_hw(struct pwm_chip *chip,
 		writel(val, tpm->base + PWM_IMX_TPM_SC);
 
 		/*
+		 * if the counter is disabled (CMOD == 0), programming the new
+		 * period length (MOD) will not reset the counter (CNT). If
+		 * CNT.COUNT happens to be bigger than the new MOD value then
+		 * the counter will end up being reset way too late. Therefore,
+		 * manually reset it to 0.
+		 */
+		if (!cmod)
+			writel(0x0, tpm->base + PWM_IMX_TPM_CNT);
+		/*
 		 * set period count:
 		 * if the PWM is disabled (CMOD[1:0] = 2b00), then MOD register
 		 * is updated when MOD register is written.
diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
index 6777c511622a..e4b595fc5a5e 100644
--- a/drivers/pwm/pwm-mediatek.c
+++ b/drivers/pwm/pwm-mediatek.c
@@ -121,6 +121,26 @@ static inline void pwm_mediatek_writel(struct pwm_mediatek_chip *chip,
 	writel(value, chip->regs + chip->soc->reg_offset[num] + offset);
 }
 
+static void pwm_mediatek_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
+	u32 value;
+
+	value = readl(pc->regs);
+	value |= BIT(pwm->hwpwm);
+	writel(value, pc->regs);
+}
+
+static void pwm_mediatek_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
+	u32 value;
+
+	value = readl(pc->regs);
+	value &= ~BIT(pwm->hwpwm);
+	writel(value, pc->regs);
+}
+
 static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			       int duty_ns, int period_ns)
 {
@@ -150,7 +170,10 @@ static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	do_div(resolution, clk_rate);
 
 	cnt_period = DIV_ROUND_CLOSEST_ULL((u64)period_ns * 1000, resolution);
-	while (cnt_period > 8191) {
+	if (!cnt_period)
+		return -EINVAL;
+
+	while (cnt_period > 8192) {
 		resolution *= 2;
 		clkdiv++;
 		cnt_period = DIV_ROUND_CLOSEST_ULL((u64)period_ns * 1000,
@@ -173,9 +196,16 @@ static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 	cnt_duty = DIV_ROUND_CLOSEST_ULL((u64)duty_ns * 1000, resolution);
+
 	pwm_mediatek_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);
-	pwm_mediatek_writel(pc, pwm->hwpwm, reg_width, cnt_period);
-	pwm_mediatek_writel(pc, pwm->hwpwm, reg_thres, cnt_duty);
+	pwm_mediatek_writel(pc, pwm->hwpwm, reg_width, cnt_period - 1);
+
+	if (cnt_duty) {
+		pwm_mediatek_writel(pc, pwm->hwpwm, reg_thres, cnt_duty - 1);
+		pwm_mediatek_enable(chip, pwm);
+	} else {
+		pwm_mediatek_disable(chip, pwm);
+	}
 
 out:
 	pwm_mediatek_clk_disable(chip, pwm);
@@ -183,35 +213,6 @@ out:
 	return ret;
 }
 
-static int pwm_mediatek_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
-	u32 value;
-	int ret;
-
-	ret = pwm_mediatek_clk_enable(chip, pwm);
-	if (ret < 0)
-		return ret;
-
-	value = readl(pc->regs);
-	value |= BIT(pwm->hwpwm);
-	writel(value, pc->regs);
-
-	return 0;
-}
-
-static void pwm_mediatek_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
-	u32 value;
-
-	value = readl(pc->regs);
-	value &= ~BIT(pwm->hwpwm);
-	writel(value, pc->regs);
-
-	pwm_mediatek_clk_disable(chip, pwm);
-}
-
 static int pwm_mediatek_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			      const struct pwm_state *state)
 {
@@ -221,8 +222,10 @@ static int pwm_mediatek_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		return -EINVAL;
 
 	if (!state->enabled) {
-		if (pwm->state.enabled)
+		if (pwm->state.enabled) {
 			pwm_mediatek_disable(chip, pwm);
+			pwm_mediatek_clk_disable(chip, pwm);
+		}
 
 		return 0;
 	}
@@ -232,7 +235,7 @@ static int pwm_mediatek_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		return err;
 
 	if (!pwm->state.enabled)
-		err = pwm_mediatek_enable(chip, pwm);
+		err = pwm_mediatek_clk_enable(chip, pwm);
 
 	return err;
 }