Re: [07/18] thunderbolt: Handle rejected Thunderbolt devices

[Jeremy McNicoll]

On 2018-02-27 1:26 AM, Mika Westerberg wrote:
> On Mon, Feb 26, 2018 at 12:15:28PM -0800, Jeremy McNicoll wrote:
> > On 2018-02-26 11:46 AM, Mika Westerberg wrote:
> > > On Mon, Feb 26, 2018 at 11:28:16AM -0800, Jeremy McNicoll wrote:
> > > > On 2018-02-26 5:38 AM, Mika Westerberg wrote:
> > > > > On Mon, Feb 26, 2018 at 12:20:29PM +0200, Mika Westerberg wrote:
> > > > > > On Thu, Feb 22, 2018 at 03:17:38PM -0800, Jeremy McNicoll wrote:
> > > > > > > > +	if (pkg->link_info & ICM_LINK_INFO_REJECTED) {
> > > > > > > > +		tb_info(tb, "switch at %u.%u was rejected by ICM firmware\n",
> > > > > > > > +			link, depth);
> > > > > > >
> > > > > > > This kind of condition sounds more like an error instead of info.
> > > > > > > Please bump this up to tb_WARN/tb_warn ideally tb_err().
> > > > > >
> > > > > > No, this is not an error.
> > > > >
> > > > > To be more clear, it is totally fine to have the firmware to reject some
> > > > > devices. For example in case of the new usbonly security level the
> > > > > firmware rejects other devices but the first.
> > > >
> > > > Ok. Is that kind of information available to the kernel?  What security
> > > > mode we are in?
> > > >
> > > > ie) if (LINK_REJECTED && !USB_SECURITY)
> > > >          print "Error switch %u was rejected since its not usbonly"
> > > >       endif
> > > >
> > > > I am sure something like that simplified pseudo code above would
> > > > be somewhat useful to users when debugging.
> > >
> > > That's why it is on info level so it goes to dmesg but does not scare
> > > the user :-)
> >
> > The point I am trying to make is that it would be nice to be able to
> > know WHY the link was rejected and not just that it was rejected.
>
> Fair enough. In practice (since we ask the firmware to accept any
> device) the only reason for rejection is that the topology limit is
> exceeded (too many devices in the chain).
>
> I'm thinking to change the message to something like:
>
> 	tb_info(tb, "switch at %u.%u was rejected by ICM firmware because topology limit exceeded\n",
> 		link, depth);
>
> And do the same for Titan Ridge in patch [18/18].
>
> Security level can be read directly from "security" sysfs attribute of
> the domain so that information does not need to be duplicated IMHO.
>
> Does that work for you?


Sounds good to me.



-jeremy