On Fri, Mar 05, 2021 at 03:17:37PM +0800, Chien Kun Niu wrote:

Greg KH [off-list ref] 於 2021年3月3日 週三 下午5:10寫道：

quoted

On Wed, Mar 03, 2021 at 05:03:25PM +0800, Chien Kun Niu wrote:

quoted

Hi , Greg

What tool will "catch" this?  Where is that code located at?
=> I prepare merge the code to Android phone , so I used Android HLOS
to catch this uevent.

Very odd quoting style, perhaps you might want to read up on how to do
this properly at:
        https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

quoted

uevents are not for stuff like this, you are trying to send "error
conditions" to userspace, please use the "proper" interfaces like this
and not abuse existing ones.
=> Sorry , I am not sure what is the "proper" interfaces your mean.
     Could you please give me more description?

How does the kernel normally send error conditions that it detects in
hardware to userspace?

I will create a sysfs attribute to record the hub status.
If there is a new hub with over 6 USB TOPO layer connected, I will use
the sysfs_notify to send the "error conditions" to userspace.
Is it a proper interfaces to delivery "error conditions"?

Maybe, it all depends on what you are wanting to show here.  Try it out
and see, it's easier to review patches that you have shown work properly
for your use case than it is to try to discuss general issues.

thanks,

greg k-h