Re: [RFC 1/2] USB: Notify OTG errors to user space via uevents

[Greg KH <greg@kroah.com>]

On Tue, Dec 07, 2010 at 09:18:32AM +0530, Pavan Kondeti wrote:
> On 12/7/2010 8:02 AM, pkondeti@codeaurora.org wrote:
> > Hi Greg,
> > 
> >> On Mon, Dec 06, 2010 at 06:07:50PM +0530, Pavankumar Kondeti wrote:
> >>> OTG specification mandates no silent failures and all errors should
> >>> be reported to the user.  The spec itself does not give the exact
> >>> error description. But recommends the error message to be self
> >>> explanatory.  Provide otg_notify_error() utility for USB core and
> >>> OTG driver to send the error codes to user space.  All the error
> >>> code values are described in include/linux/usb/ch9.h.  The user space
> >>> application can listen to netlink socket and parse the buffer for
> >>> "MODULE=OTG" and "ERROR=n", where 'n' contains the error code.
> >>
> >> How are you going to listen to the netlink socket that is already
> >> grabbed by libudev?
> >>
> > Sorry. I never worked with udev. But I read udev documentation.
> > I thought an external script can be invoked by adding a udev rule
> > when MODULE=OTG is matched and ERROR value can be accessed
> > in the script via env variable.
> > 
> I ran the sample program @ http://www.kernel.org/doc/pending/hotplug.txt
> and udevd concurrently. I am able to capture all the uevents in sample
> program.

Interesting, but what userspace tool are you going to create to listen
to these events that all distros are now going to have to use?

Again, please, this is NOT the interface to get errors out of the kernel
for something as minor as USB OTG issues that we have been successfully
handling just fine for years now.

thanks,

greg k-h