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author | Fabrice Gasnier <fabrice.gasnier@st.com> | 2018-10-01 16:23:56 +0300 |
---|---|---|
committer | Thierry Reding <thierry.reding@gmail.com> | 2018-10-12 14:51:11 +0300 |
commit | c289d6625237aa785b484b4e94c23b3b91ea7e60 (patch) | |
tree | c834725cf6230c60ed0919fd37e611f9a6d0243c /drivers/pwm/sysfs.c | |
parent | d5a7060022cd443cc6a054bc73383acac6a8f53d (diff) | |
download | linux-c289d6625237aa785b484b4e94c23b3b91ea7e60.tar.xz |
Revert "pwm: Set class for exported channels in sysfs"
This reverts commit 7e5d1fd75c3dde9fc10c4472b9368089d1b81d00 ("pwm: Set
class for exported channels in sysfs") as it causes regression with
multiple pwm chip[1], when exporting a pwm channel (echo X > export):
- ABI (Documentation/ABI/testing/sysfs-class-pwm) states pwmX should be
created in /sys/class/pwm/pwmchipN/pwmX
- Reverted patch causes new entry to be also created directly in
/sys/class/pwm/pwmX
- 1st time, exporting pwmX will create an entry in /sys/class/pwm/pwmX
- class attributes are added under pwmX folder, such as export, unexport
npwm, symlinks. This is wrong as it belongs to pwmchipN. It may cause
bad behavior and report wrong values.
- when another export happens on another pwmchip, it can't be created
(e.g. -EEXIST). This is causing the issue with multiple pwmchip.
Example on stm32 (stm32429i-eval) platform:
$ ls /sys/class/pwm
pwmchip0 pwmchip4
$ cd /sys/class/pwm/pwmchip0/
$ echo 0 > export
$ ls /sys/class/pwm
pwm0 pwmchip0 pwmchip4
$ cd /sys/class/pwm/pwmchip4/
$ echo 0 > export
sysfs: cannot create duplicate filename '/class/pwm/pwm0'
...Exception stack follows...
This is also seen on other platform [2]
[1] https://lkml.org/lkml/2018/9/25/713
[2] https://lkml.org/lkml/2018/9/25/447
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Tested-by: Gottfried Haider <gottfried.haider@gmail.com>
Tested-by: Michal Vokáč <michal.vokac@ysoft.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm/sysfs.c')
-rw-r--r-- | drivers/pwm/sysfs.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index 7c71cdb8a9d8..4726d43aaa0c 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -263,7 +263,6 @@ static int pwm_export_child(struct device *parent, struct pwm_device *pwm) export->pwm = pwm; mutex_init(&export->lock); - export->child.class = parent->class; export->child.release = pwm_export_release; export->child.parent = parent; export->child.devt = MKDEV(0, 0); |