| From 020162d6f49f2963062229814a56a89c86cbeaa8 Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de> |
| Date: Wed, 7 Jul 2021 18:27:50 +0200 |
| Subject: pwm: mxs: 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 |
| |
| From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> |
| |
| 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> |
| --- |
| drivers/pwm/pwm-mxs.c | 13 +++++-------- |
| 1 file changed, 5 insertions(+), 8 deletions(-) |
| |
| --- a/drivers/pwm/pwm-mxs.c |
| +++ b/drivers/pwm/pwm-mxs.c |
| @@ -145,6 +145,11 @@ static int mxs_pwm_probe(struct platform |
| 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 |
| |
| 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) |
