Re: [RFC/PATCH 2/2] driver core: power management debugging

[Greg KH <greg@kroah.com>]

On Sun, Apr 29, 2007 at 08:55:52AM +1000, Nigel Cunningham wrote:
> Hi.
> 
> On Sat, 2007-04-28 at 10:42 -0400, Alan Stern wrote:
> > On Sat, 28 Apr 2007, Nigel Cunningham wrote:
> > 
> > > Hi Alan.
> > 
> > > Sorry. I thought you were wrong for a minute, but then I looked again at
> > > the messages in my dmesg...
> > > 
> > > [   33.944214] Device driver usbdev1.1_ep00 lacks bus and class support for being resumed.
> > > [   34.051765] Device driver usbdev1.1_ep81 lacks bus and class support for being resumed.
> > > [   34.113740] Device driver usbdev2.1_ep00 lacks bus and class support for being resumed.
> > > [   34.221541] Device driver usbdev2.1_ep81 lacks bus and class support for being resumed.
> > > [   34.251562] Device driver usbdev3.1_ep00 lacks bus and class support for being resumed.
> > > [   34.361345] Device driver usbdev3.1_ep81 lacks bus and class support for being resumed.
> > > 
> > > They're coming from the other printk, of course.
> > > 
> > > > Now perhaps you would prefer to check the USB interface drivers -- there 
> > > > are many of them, and quite a few don't have suspend or resume methods.  
> > > > You would need to modify usb_register_driver() instead of 
> > > > usb_register_device_driver().
> > > 
> > > Would they be the ones covered above?
> > 
> > No.  As Greg pointed out, these usbdevXX_epYY "devices" are nothing but 
> > placeholders at the moment.  They don't actually do anything and they have 
> > no need for power management.  (But they do manage to clutter up the 
> > system log with lots of extraneous warnings from the PM core...)
> 
> Ok, so they could have the pm_safe flag set to suppress the message.

No, we don't want a flag just to shut up a message, that's the first
thing a developer will do when they see that message, without realizing
what exactly they should be doing instead.

Trust me, I know the lengths kernel developers go to to try to work
around "helpful hints" that the kernel can spit out at you :(

thanks,

greg k-h