[PATCH v2] pwm: imx-tpm: keep channel state instead of counting
From: Viorel Suman (OSS) <hidden>
Date: 2026-02-02 10:47:43
Also in:
imx, linux-pwm, lkml
Subsystem:
pwm subsystem, the rest · Maintainers:
Uwe Kleine-König, Linus Torvalds
On a soft reset TPM PWM IP may preserve its internal state from
previous runtime, therefore on a subsequent OS boot and driver
probe "enable_count" value and TPM PWM IP internal channels
"enabled" states may get unaligned. In consequence on a suspend/resume
cycle the call "if (--tpm->enable_count == 0)" may lead to
"enable_count" overflow the system being blocked from entering
suspend due to:
if (tpm->enable_count > 0)
return -EBUSY;
Fix the problem by replacing counting logic with per-channel state
handling and by aligning IP and driver state at probe.
Signed-off-by: Viorel Suman (OSS) <redacted>
---
Changes since v1:
1. Moved device state check into the probe function.
2. Dropped {} for one line blocks.
drivers/pwm/pwm-imx-tpm.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
index 5b399de16d60..c87688dfd406 100644
--- a/drivers/pwm/pwm-imx-tpm.c
+++ b/drivers/pwm/pwm-imx-tpm.c@@ -62,7 +62,7 @@ struct imx_tpm_pwm_chip { void __iomem *base; struct mutex lock; u32 user_count; - u32 enable_count; + u32 enabled_channels; u32 real_period; };
@@ -282,14 +282,16 @@ static int pwm_imx_tpm_apply_hw(struct pwm_chip *chip, } writel(val, tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm)); - /* control the counter status */ + /* control the channel state */ if (state->enabled != c.enabled) { val = readl(tpm->base + PWM_IMX_TPM_SC); if (state->enabled) { - if (++tpm->enable_count == 1) + if (tpm->enabled_channels == 0) val |= PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK; + tpm->enabled_channels |= BIT(pwm->hwpwm); } else { - if (--tpm->enable_count == 0) + tpm->enabled_channels &= ~BIT(pwm->hwpwm); + if (tpm->enabled_channels == 0) val &= ~PWM_IMX_TPM_SC_CMOD; } writel(val, tpm->base + PWM_IMX_TPM_SC);
@@ -353,7 +355,7 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev) void __iomem *base; int ret; unsigned int npwm; - u32 val; + u32 val, i; base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(base))
@@ -382,6 +384,13 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev) mutex_init(&tpm->lock); + /* get enabled state for each channel */ + for (i = 0; i < npwm; i++) { + val = readl(base + PWM_IMX_TPM_CnSC(i)); + if (FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val)) + tpm->enabled_channels |= BIT(i); + } + ret = devm_pwmchip_add(&pdev->dev, chip); if (ret) return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");
@@ -394,7 +403,7 @@ static int pwm_imx_tpm_suspend(struct device *dev) struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev); int ret; - if (tpm->enable_count > 0) + if (tpm->enabled_channels > 0) return -EBUSY; /*
--
2.34.1