linux-kernel - Re: [PATCH 2/2] thunderbolt: Initialize after IOMMUs

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Message-ID: <20180906110049.gfdhurvkvvdjw7zh@wunner.de>
Date:   Thu, 6 Sep 2018 13:00:49 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: Re: [PATCH 2/2] thunderbolt: Initialize after IOMMUs

On Thu, Sep 06, 2018 at 01:36:02PM +0300, Mika Westerberg wrote:
> On Thu, Sep 06, 2018 at 10:13:37AM +0200, Lukas Wunner wrote:
> > So with this patch, you rely on the linker ordering nhi_init() after
> > ir_dev_scope_init(), however to the best of my knowledge the link
> > order is not guaranteed.
> 
> What says that?

Within the same initcall level, the ordering is determined by the Makefile
AFAIK.  Someone changes the Makefile, your dependency scheme falls apart.


> > Looking at commit acb40d841257, which started this, I'm wondering
> > why you did not simply export tbnet_init() and call it from the
> > thunderbolt driver after the property stuff has been fully set up?
> > After all, thunderbolt-net is useless without thunderbolt or am I
> > missing something?  Then you could revert back to module_init().
> 
> The same reason you don't call PCI driver functions from PCI core. It
> makes absolutely zero sense.
> 
> Thunderbolt is bus and provides driver API to drivers. We hopefully are
> getting other service drivers (say SCSI over TBT) that are going to be
> use the same interfaces.

Then add a blocking notifier chain into which these service drivers can
hook.  Other buses have that as well.

Thanks,

Lukas