On Tue, May 19, 2020 at 11:41:45AM +0000, Geva, Erez wrote:
> From a quick look.
> It seems that it is 'pwmchip%d' for a long time.
>
> https://elixir.bootlin.com/linux/v4.0/source/drivers/pwm/sysfs.c#L314
Looks like my v4.19.25-rt16 kernel has a bad commit with a regression.
The documentation, Documentation/ABI/testing/sysfs-class-pwm, is
clear, and it has been that way since kernel 3.11.
Mainline has this:
commit c289d6625237aa785b484b4e94c23b3b91ea7e60
Author: Fabrice Gasnier <fabrice.gasn...@st.com>
Date: Mon Oct 1 15:23:56 2018 +0200
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.
_______________________________________________
Linuxptp-devel mailing list
Linuxptp-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
