Re: [PATCH v2] pwm: imx-tpm: keep channel state instead of counting

[Uwe Kleine-König]

Hello,

On Mon, Feb 02, 2026 at 12:47:38PM +0200, Viorel Suman (OSS) wrote:
> 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) <viorel.suman@xxxxxxxxxxx>

I wonder if the following change would be enough:

diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
index 5b399de16d60..36f873133f94 100644
--- a/drivers/pwm/pwm-imx-tpm.c
+++ b/drivers/pwm/pwm-imx-tpm.c
@@ -352,7 +352,7 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev)
 	struct clk *clk;
 	void __iomem *base;
 	int ret;
-	unsigned int npwm;
+	unsigned int i, npwm;
 	u32 val;
 
 	base = devm_platform_ioremap_resource(pdev, 0);
@@ -382,6 +382,12 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev)
 
 	mutex_init(&tpm->lock);
 
+	for (i = 0; i < npwm; ++i) {
+		val = readl(base + PWM_IMX_TPM_CnSC(i));
+		if (FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val))
+			++tpm->enable_count;
+	}
+
 	ret = devm_pwmchip_add(&pdev->dev, chip);
 	if (ret)
 		return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");

Best regards
Uwe

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