Date: Fri, 30 Nov 2012 07:52:34 +0100
From: Thierry Reding <thierry.reding@avionic-design.de>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Terje =?utf-8?Q?Bergstr=C3=B6m?= <tbergstrom@nvidia.com>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC v2 1/8] video: tegra: Add nvhost driver
Message-ID: <20121130065234.GC26474@avionic-0098.adnet.avionic-design.de>
References: <1353935954-13763-1-git-send-email-tbergstrom@nvidia.com>
 <1353935954-13763-2-git-send-email-tbergstrom@nvidia.com>
 <20121128212301.GA25531@avionic-0098.adnet.avionic-design.de>
 <50B73710.2040102@nvidia.com>
 <20121129114704.GB6150@avionic-0098.adnet.avionic-design.de>
 <50B7AB93.5060207@wwwdotorg.org>
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On Thu, Nov 29, 2012 at 11:38:11AM -0700, Stephen Warren wrote:
> On 11/29/2012 04:47 AM, Thierry Reding wrote:
> > On Thu, Nov 29, 2012 at 12:21:04PM +0200, Terje Bergstr=C3=B6m wrote:
> >> On 28.11.2012 23:23, Thierry Reding wrote:
> >>> This could be problematic. Since drivers/video and
> >>> drivers/gpu/drm are separate trees, this would entail a
> >>> continuous burden on keeping both trees synchronized. While I
> >>> realize that eventually it might be better to put the host1x
> >>> driver in a separate place to accomodate for its use by other
> >>> subsystems, I'm not sure moving it here right away is the best=20
> >>> approach.
> >>=20
> >> I understand your point, but I hope also that we'd end up with
> >> something that can be used as basis for the downstream kernel to
> >> migrate to upstream stack.
> >>=20
> >> The key point here is to make the API between nvhost and tegradrm
> >> as small and robust to changes as possible.
> >=20
> > I agree. But I also fear that there will be changes eventually and=20
> > having both go in via different tree requires those trees to be
> > merged in a specific order to avoid breakage should the API change.
> > This will be particularly ugly in linux-next.
> >=20
> > That's why I explicitly proposed to take this into
> > drivers/gpu/drm/tegra for the time being, until we can be
> > reasonably sure that the API is fixed. Then I'm fine with moving it
> > wherever seems the best fit. Even then there might be the
> > occasional dependency, but they should get fewer and fewer as the
> > code matures.
>=20
> It is acceptable for one maintainer to ack patches, and another
> maintainer to merge a series that touches both "their own" code and
> code owned by another tree. This should of course only be needed when
> inter-module APIs change; changes to code within a module shouldn't
> require this.

Yes, that's true. But it still makes things more complicated since each
of the maintainers will have to do extra work to test the changes.
Anyway we'll see how this plays out. The ideal case would of course be
to get the API right from the start. =3D)

Thierry

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