Commit 020162d6 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Thierry Reding
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pwm: mxs: Don't modify HW state in .probe() after the PWM chip was registered 



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 reset before calling pwmchip_add().

Note that reseting the hardware isn't the right thing to do if the PWM
is already running as it might e.g. disable (or even enable) a backlight
that is supposed to be on (or off).

Fixes: 4dce82c1 ("pwm: add pwm-mxs support")
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 3d2813fb

drivers/pwm/pwm-mxs.c

+5 −8
Original line number Diff line number Diff line
@@ -145,6 +145,11 @@ static int mxs_pwm_probe(struct platform_device *pdev) 
		return ret;

	}



	/* FIXME: Only do this if the PWM isn't already running */

	ret = stmp_reset_block(mxs->base);

	if (ret)

		return dev_err_probe(&pdev->dev, ret, "failed to reset PWM\n");



	ret = pwmchip_add(&mxs->chip);

	if (ret < 0) {

		dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
@@ -153,15 +158,7 @@ static int mxs_pwm_probe(struct platform_device *pdev) 


	platform_set_drvdata(pdev, mxs);



	ret = stmp_reset_block(mxs->base);

	if (ret)

		goto pwm_remove;



	return 0;



pwm_remove:

	pwmchip_remove(&mxs->chip);

	return ret;

}



static int mxs_pwm_remove(struct platform_device *pdev)