linux-kernel - [PATCH] pwm: imx-tpm: force 'real

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Date:   Fri,  5 May 2023 14:58:39 +0800
From:   Clark Wang <xiaoning.wang@....com>
To:     thierry.reding@...il.com, u.kleine-koenig@...gutronix.de,
        shawnguo@...nel.org, s.hauer@...gutronix.de, festevam@...il.com
Cc:     kernel@...gutronix.de, linux-imx@....com,
        linux-pwm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] pwm: imx-tpm: force 'real_period' to be zero in suspend

From: Fancy Fang <chen.fang@....com>

During suspend, all the tpm registers will lose values.
So the 'real_period' value of struct 'imx_tpm_pwm_chip'
should be forced to be zero to force the period update
code can be executed after system resume back.

Signed-off-by: Fancy Fang <chen.fang@....com>
Signed-off-by: Clark Wang <xiaoning.wang@....com>
---
 drivers/pwm/pwm-imx-tpm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
index 5e2b452ee5f2..98ab65c89685 100644
--- a/drivers/pwm/pwm-imx-tpm.c
+++ b/drivers/pwm/pwm-imx-tpm.c
@@ -397,6 +397,13 @@ static int __maybe_unused pwm_imx_tpm_suspend(struct device *dev)
 	if (tpm->enable_count > 0)
 		return -EBUSY;
 
+	/*
+	 * Force 'real_period' to be zero to force period update code
+	 * can be executed after system resume back, since suspend causes
+	 * the period related registers to become their reset values.
+	 */
+	tpm->real_period = 0;
+
 	clk_disable_unprepare(tpm->clk);
 
 	return 0;
-- 
2.34.1