linux-kernel - [PATCH v3 4/4] pwm: imx27: return error, if clean PWM setup fails

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Date:   Tue, 15 Aug 2023 12:43:32 +0200
From:   Leif Middelschulte <leif.middelschulte@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Cc:     Leif Middelschulte <Leif.Middelschulte@...il.com>,
        linux-pwm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 4/4] pwm: imx27: return error, if clean PWM setup fails

Instead of issuing a warning, return an error (as adviced[0]), if the
FIFO cannot be cleanly set up.

[0] https://lore.kernel.org/lkml/20230310174517.rb7xxrougkse2lrc@pengutronix.de/T/#ec9560c1f613d9c0d7b77d72ad9051768812f80db

Signed-off-by: Leif Middelschulte <Leif.Middelschulte@...il.com>
---
 drivers/pwm/pwm-imx27.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
index 9673e809d212..5fd6d34a7722 100644
--- a/drivers/pwm/pwm-imx27.c
+++ b/drivers/pwm/pwm-imx27.c
@@ -133,14 +133,15 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip,
 		sr = readl(imx->mmio_base + MX3_PWMSR);
 		fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);
 		if (fifoav == MX3_PWMSR_FIFOAV_EMPTY)
-			return;
+			return 0;
 		/* if the FIFO value does not decrease, there is another problem */
 		if (previous_fifoav == fifoav)
 			break;
 		previous_fifoav = fifoav;
 		msleep(period_ms);
 	}
-	dev_warn(dev, "FIFO has been refilled concurrently\n");
+
+	return -EAGAIN;
 }
 
 static int pwm_imx27_get_state(struct pwm_chip *chip,
@@ -208,7 +209,9 @@ static int pwm_imx27_get_state(struct pwm_chip *chip,
 		 * been supplied and a period expired between the call of the wait
 		 * function and the subsequent readl.
 		 */
-		pwm_imx27_wait_fifo_empty(chip, pwm);
+		ret = pwm_imx27_wait_fifo_empty(chip, pwm);
+		if (ret)
+			return ret;
 		val = readl(imx->mmio_base + MX3_PWMSAR);
 	} else {
 		val = imx->duty_cycle;
-- 
2.39.2 (Apple Git-143)