From 7fc2172ad4e701d3c6e7dcb7b2efd8df71d2417b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Wed, 7 Jul 2021 18:27:49 +0200 Subject: [PATCH] pwm: lpc32xx: Don't modify HW state in .probe() after the PWM chip was registered MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 3d2813fb17e5fd0d73c1d1442ca0192bde4af10e upstream. This fixes a race condition: After pwmchip_add() is called there might already be a consumer and then modifying the hardware behind the consumer's back is bad. So set the default before. (Side-note: I don't know what this register setting actually does, if this modifies the polarity there is an inconsistency because the inversed polarity isn't considered if the PWM is already running during .probe().) Fixes: acfd92fdfb93 ("pwm: lpc32xx: Set PWM_PIN_LEVEL bit to default value") Cc: Sylvain Lemieux Signed-off-by: Uwe Kleine-König Signed-off-by: Thierry Reding Signed-off-by: Greg Kroah-Hartman --- drivers/pwm/pwm-lpc32xx.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/pwm/pwm-lpc32xx.c b/drivers/pwm/pwm-lpc32xx.c index a9b3cff96aac..ed8e9406b4af 100644 --- a/drivers/pwm/pwm-lpc32xx.c +++ b/drivers/pwm/pwm-lpc32xx.c @@ -124,17 +124,17 @@ static int lpc32xx_pwm_probe(struct platform_device *pdev) lpc32xx->chip.npwm = 1; lpc32xx->chip.base = -1; + /* If PWM is disabled, configure the output to the default value */ + val = readl(lpc32xx->base + (lpc32xx->chip.pwms[0].hwpwm << 2)); + val &= ~PWM_PIN_LEVEL; + writel(val, lpc32xx->base + (lpc32xx->chip.pwms[0].hwpwm << 2)); + ret = pwmchip_add(&lpc32xx->chip); if (ret < 0) { dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret); return ret; } - /* When PWM is disable, configure the output to the default value */ - val = readl(lpc32xx->base + (lpc32xx->chip.pwms[0].hwpwm << 2)); - val &= ~PWM_PIN_LEVEL; - writel(val, lpc32xx->base + (lpc32xx->chip.pwms[0].hwpwm << 2)); - platform_set_drvdata(pdev, lpc32xx); return 0;