Re: About TRB_TO_EP_INDEX() macro using

['gregkh@xxxxxxxxxxxxxxxxxxx']

On Tue, Aug 06, 2013 at 08:59:32AM +0000, Du, ChangbinX wrote:
> > On Mon, Aug 05, 2013 at 08:07:25AM +0000, Du, ChangbinX wrote:
> > > Recently when I check xHCI code, find that some functions try to get EP index
> > > from a Command Completion Event TRB via TRB_TO_EP_INDEX() macro.
> > >
> > > This is totally wrong. The macro definition is:
> > >
> > > 	#define TRB_TO_EP_INDEX(p)		((((p) & (0x1f << 16)) >> 16) - 1)
> > >
> > > TRB_TO_EP_INDEX only applies to Transfer Event TRB. But for Command
> > > Completion Event TRB, there is no Endpoint ID field. So, we cannot directly
> > > get EP index from these TRBs, but we can find it by the TRB Pointer.
> > >
> > > Here list two functions for you to check:
> > > 	handle_stopped_endpoint()
> > > 	handle_reset_ep_completion()
> > 
> > Care to send a patch showing how you would change this if it is
> > incorrect?
> > 
> > thanks,
> > 
> > greg k-h
> > --
> 
> Hello, Greg k-h. I am not very sure about this issue. If this is true, kernel will panic when 
> invoking above functions. I want someone help to confirm if I miss something. If it's really 
> a bug, I will work out a patch to fix it.

That's not how kernel development works, sorry.  If you think this is an
issue, try to reproduce it and then create a patch.

thanks,

greg k-h
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