diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0310-Revert-pwm-Set-class-for-exported-channels-in-sysfs.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.19/950-0310-Revert-pwm-Set-class-for-exported-channels-in-sysfs.patch | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0310-Revert-pwm-Set-class-for-exported-channels-in-sysfs.patch b/target/linux/brcm2708/patches-4.19/950-0310-Revert-pwm-Set-class-for-exported-channels-in-sysfs.patch new file mode 100644 index 0000000000..ea8a2b2c06 --- /dev/null +++ b/target/linux/brcm2708/patches-4.19/950-0310-Revert-pwm-Set-class-for-exported-channels-in-sysfs.patch @@ -0,0 +1,63 @@ +From d499c8f6171122d78a90c3a6403ac7c0c1f50887 Mon Sep 17 00:00:00 2001 +From: Fabrice Gasnier <fabrice.gasnier@st.com> +Date: Mon, 1 Oct 2018 15:23:56 +0200 +Subject: [PATCH 310/703] Revert "pwm: Set class for exported channels in + sysfs" +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +commit c289d6625237aa785b484b4e94c23b3b91ea7e60 upstream. + +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> +--- + drivers/pwm/sysfs.c | 1 - + 1 file changed, 1 deletion(-) + +--- a/drivers/pwm/sysfs.c ++++ b/drivers/pwm/sysfs.c +@@ -263,7 +263,6 @@ static int pwm_export_child(struct devic + 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); |