From: Uwe Kleine-König Date: Wed, 7 Jul 2021 16:27:50 +0000 (+0200) Subject: pwm: mxs: Don't modify HW state in .probe() after the PWM chip was registered X-Git-Tag: microblaze-v5.16~24^2~50 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=020162d6f49f2963062229814a56a89c86cbeaa8;p=linux-2.6-microblaze.git 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: 4dce82c1e840 ("pwm: add pwm-mxs support") Cc: Sascha Hauer Cc: Shawn Guo Signed-off-by: Uwe Kleine-König Signed-off-by: Thierry Reding --- diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c index a22180803bd7..558dc1de8f5d 100644 --- a/drivers/pwm/pwm-mxs.c +++ b/drivers/pwm/pwm-mxs.c @@ -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)