diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2021-07-07 19:27:50 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-26 15:08:58 +0300 |
| commit | 777344da345a374eb74f2a743b5399e6e60d566b (patch) | |
| tree | cb71fdb86c9b102cc4383b9258e95f534dd42ca5 | |
| parent | 322b70b522abe03cd59712bb47a72eddd835d19d (diff) | |
| download | linux-777344da345a374eb74f2a743b5399e6e60d566b.tar.xz | |
pwm: mxs: Don't modify HW state in .probe() after the PWM chip was registered
commit 020162d6f49f2963062229814a56a89c86cbeaa8 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 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 <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/pwm/pwm-mxs.c | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c index 7ce616923c52..41bdbe71ae46 100644 --- a/drivers/pwm/pwm-mxs.c +++ b/drivers/pwm/pwm-mxs.c @@ -148,6 +148,11 @@ 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); @@ -156,15 +161,7 @@ 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) |