Message-ID: <1380667491.10618.67.camel@snotra.buserror.net>
Subject: Re: RFC: (re-)binding the VFIO platform driver to a platform device
From: Scott Wood <scottwood@freescale.com>
To: Kim Phillips <kim.phillips@linaro.org>
CC: <linux-kernel@vger.kernel.org>, <gregkh@linuxfoundation.org>,
        <a.motakis@virtualopensystems.com>, <agraf@suse.de>,
        <alex.williamson@redhat.com>, <stuart.yoder@freescale.com>,
        <B07421@freescale.com>, <B16395@freescale.com>, <R65777@freescale.com>,
        <peter.maydell@linaro.org>, <christoffer.dall@linaro.org>,
        <santosh.shukla@linaro.org>, <kvm@vger.kernel.org>
Date: Tue, 1 Oct 2013 17:44:51 -0500
In-Reply-To: <20131001165914.a7ebe64aac3e4bb0f845da29@linaro.org>
References: <20131001133831.6e46e8e00e09d5d9079fde57@linaro.org>
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On Tue, 2013-10-01 at 16:59 -0500, Kim Phillips wrote:
> On Tue, 1 Oct 2013 14:15:38 -0500
> Scott Wood <scottwood@freescale.com> wrote:
> 
> > I think the ideal interface would be if you could write the sysfs device
> > name into the vfio bind file (or some new file in the same directory),
> > and have it claim that device (preferably with an atomic unbind from the
> > previous driver).
> 
> ok.

...which apparently is what you are already doing (except for the atomic
part).  My recollection of how this works on PCI (via new_id) apparently
kept me from reading it properly. :-P

> > We shouldn't be messing around with compatible
> > (either modifying it or telling VFIO which compatibles to look for) when
> > we know the specific devices (not just type of devices) we want to bind.
> 
> ok, but I still don't see how to get past driver_match_device()'s
> refusal to allow bind a non-compatible driver (or one who's name isn't
> in the compatible list).

Probably something similar to your hack, except use a flag or some other
neutral mechanism rather than a driver name.

The flag could be something like "I'll try to bind to any device on this
bus, but only if explicitly requested".

-Scott


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