On Tue, Nov 26, 2019 at 12:08:18PM +0900, Chanwoo Choi wrote:
Hi Greg,
On 11/25/19 5:50 PM, Greg KH wrote:
On Mon, Nov 25, 2019 at 10:03:57AM +0900, Chanwoo Choi wrote:
The commit 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs") changed the node name to devfreq(x). After this commit, it is not possible to get the device name through /sys/class/devfreq/devfreq(X)/*.
Add new name attribute in order to get device name.
Cc: stable@vger.kernel.org Fixes: 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs") Signed-off-by: Chanwoo Choi cw00.choi@samsung.com
Changes from v2:
- Change the order of name_show() according to the sequence in devfreq_attrs[]
Changes from v1:
- Update sysfs-class-devfreq documentation
- Show device name directly from 'devfreq->dev.parent'
Shouldn't you just revert the original patch here? Why did the sysfs file change?
The initial devfreq code used the parent device name for device name corresponding to devfreq object instead of 'devfreq%d' style. Before applied The commit 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs"), the devfreq sysfs showed the parent device name as following:
For example on Odroid-XU3 board before applied the commit 4585fbcb5331, /sys/class/devfreq/soc:bus_wcore /sys/class/devfreq/soc:bus_noc ...(skip)
But, I think that devfreq subsystem had to show the consistent sysfs entry name for devfreq device like input, thermal, hwmon subsystem.
For example on Odroid-XU3 board,
- The input subsystem show the 'input%d' style for input device.
$root@localhost:/# ls /sys/class/input/ event0 event1 input0 input1 mice mouse0
- The thermal subsystem show the 'cooling_device%d' style for thermal cooling device.
$ root@localhost:/# ls /sys/class/thermal/ cooling_device0 cooling_device2 thermal_zone1 thermal_zone3 cooling_device1 thermal_zone0 thermal_zone2 thermal_zone4
- The hwmon subsystem show the 'hwmon%d' style for h/w monitor device.
$root@localhost:/# ls /sys/class/hwmon/ hwmon0
So, I tried to make the consistent sysfs entry name for devfreq device by contributing commit 4585fbcb5331 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs"). But, The commit 4585fbcb5331 have missed that sysfs interface had to provide the real device name. Some subsystem like thermal and hwmon provide the device type or device name through sysfs interface. It is possible to make the user to find their own specific device by iteration on user-space.
root@localhost:/# cat /sys/class/thermal/cooling_device0/type pwm-fan root@localhost:/# cat /sys/class/thermal/cooling_device1/type thermal-cpufreq-0 root@localhost:/# cat /sys/class/thermal/cooling_device2/type thermal-cpufreq-1
root@localhost:/# cat /sys/class/hwmon/hwmon0/name pwmfan
So, I add the new 'name' attribute of sysfs for devfreq device.
Documentation/ABI/testing/sysfs-class-devfreq | 7 +++++++ drivers/devfreq/devfreq.c | 9 +++++++++ 2 files changed, 16 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq index 01196e19afca..75897e2fde43 100644 --- a/Documentation/ABI/testing/sysfs-class-devfreq +++ b/Documentation/ABI/testing/sysfs-class-devfreq @@ -7,6 +7,13 @@ Description: The name of devfreq object denoted as ... is same as the name of device using devfreq. +What: /sys/class/devfreq/.../name +Date: November 2019 +Contact: Chanwoo Choi cw00.choi@samsung.com +Description:
The /sys/class/devfreq/.../name shows the name of deviceof the corresponding devfreq object.What: /sys/class/devfreq/.../governor Date: September 2011 Contact: MyungJoo Ham myungjoo.ham@samsung.com diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 65a4b6cf3fa5..6f4d93d2a651 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1169,6 +1169,14 @@ int devfreq_remove_governor(struct devfreq_governor *governor) } EXPORT_SYMBOL(devfreq_remove_governor); +static ssize_t name_show(struct device *dev,
struct device_attribute *attr, char *buf)+{
- struct devfreq *devfreq = to_devfreq(dev);
- return sprintf(buf, "%s\n", dev_name(devfreq->dev.parent));
Why is the parent's name being set here, and not the device name?
The device name style in struct devfreq is 'devfreq%d' instead of parent device name in order to keep the consistent naming style for devfreq device as I mentioned above. 'devfreq%d' name is consistent name style for devfreq device. But, it don't show the real h/w device name. So, show the parent device name which is specified on device-tree file.
I'm sorry, but I still do not understand. Can you show me the directory tree before and after here?
thanks,
greg k-h