From: Thierry Reding <thierry.reding@avionic-design.de>
To: "Terje Bergström" <tbergstrom@nvidia.com>
Cc: "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>,
Arto Merilainen <amerilainen@nvidia.com>
Subject: Re: [RFC v2 6/8] gpu: drm: tegra: Remove redundant host1x
Date: Wed, 5 Dec 2012 13:04:29 +0100 [thread overview]
Message-ID: <20121205120429.GA29943@avionic-0098.adnet.avionic-design.de> (raw)
In-Reply-To: <50BF345A.8050201@nvidia.com>
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On Wed, Dec 05, 2012 at 01:47:38PM +0200, Terje Bergström wrote:
> On 05.12.2012 13:13, Thierry Reding wrote:
[...]
> > Oh well, at the time nobody from NVIDIA was involved so I wrote that
> > code in preparation for proper host1x support that I thought I would
> > have to add myself at some point. I'm more than glad that I don't have
> > to do this all by myself. However the patch proposed in this series
> > breaks a number of requirements such as proper encapsulation, which I
> > already mentioned in more detail in another mail.
>
> Hmm, I'm not sure if I remember that you refer to by the proper
> encapsulation. Is that the fact that we bind DRM to a sub-client?
Yes, but there's more. For instance I went to great lengths to make sure
there's no global data whatsoever. So all the data is bound to the
host1x device in the current code. I know many other drivers like to
take a shortcut and just put these things into global variables but I
didn't want to.
> > The problem that this solves is that the DRM driver needs to be bound to
> > a specific platform device. None of the DRM subdevices are suitable
> > because they are only part of the whole DRM device. I think that host1x
> > is the only device that fits here.
> >
> > Note that this is only an administrative problem. It shouldn't interfere
> > with the way host1x works. The goal is that the DRM device is registered
> > at the proper hierarchical location.
> >
> > The circular dependency is indeed a problem, though. Quite frankly I
> > have no idea how to solve this. However the approach taken in the
> > current patch will break several other requirements as I already
> > explained.
>
> The problem with doing drm_platform_init() with host1x device as
> parameter is that drm_get_platform_dev() will take control of drvdata.
> We'd need to put host1x specific struct host1x pointer to some other
> place and I'm not sure what that place could be.
Not anymore. I submitted a patch so that it no longer does that. The
patch was merged about a month and a half ago.
> You're right in that binding to a sub-device is not a nice way. DRM
> framework just needs a "struct device" to bind to. exynos seems to solve
> this by introducing a virtual device and bind to that. I'm not sure if
> this is the best way, but worth considering?
That was discussed a few months back already and nobody seemed to like
the idea. In fact it was as a result of that discussion that Stephen
brought up the idea to register the DRM driver from a central host1x
driver (it may also have been part of a discussion on IRC, I don't
remember exactly).
At the time I spent some time on a patch that introduced drm_soc_init()
to solve this by creating a dummy struct device and registering the
driver on top of that. But I abandoned it in favour of fixing the DRM
platform support code. The approach also didn't provide for the proper
encapsulation.
Thierry
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next prev parent reply other threads:[~2012-12-05 12:04 UTC|newest]
Thread overview: 145+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-26 13:19 [RFC v2 0/8] Support for Tegra 2D hardware Terje Bergstrom
2012-11-26 13:19 ` [RFC v2 1/8] video: tegra: Add nvhost driver Terje Bergstrom
2012-11-27 10:52 ` Sivaram Nair
2012-11-28 21:23 ` Thierry Reding
2012-11-29 10:21 ` Terje Bergström
2012-11-29 11:47 ` Thierry Reding
2012-11-29 18:38 ` Stephen Warren
2012-11-30 6:52 ` Thierry Reding
2012-11-30 8:50 ` Lucas Stach
2012-12-01 11:44 ` Terje Bergström
2012-12-01 15:10 ` Thierry Reding
2012-12-01 16:55 ` Terje Bergström
2012-12-01 17:34 ` Lucas Stach
2012-12-01 19:29 ` Terje Bergström
2012-12-01 21:42 ` Dave Airlie
2012-12-01 22:39 ` Thierry Reding
2012-12-02 11:24 ` Terje Bergström
2012-12-02 20:55 ` Thierry Reding
2012-12-03 6:26 ` Terje Bergström
2012-11-30 8:56 ` Terje Bergström
2012-11-30 10:38 ` Thierry Reding
2012-12-01 11:31 ` Terje Bergström
2012-12-01 13:42 ` Daniel Vetter
2012-12-01 16:22 ` Terje Bergström
2012-12-01 14:58 ` Thierry Reding
2012-12-01 17:13 ` Terje Bergström
2012-12-03 19:23 ` Stephen Warren
2012-12-04 21:31 ` Thierry Reding
2012-12-03 19:20 ` Stephen Warren
2012-12-03 21:03 ` Thierry Reding
2012-12-04 2:08 ` Mark Zhang
2012-12-04 2:11 ` Mark Zhang
2012-12-04 6:17 ` Terje Bergström
2012-11-29 18:34 ` Stephen Warren
2012-11-30 6:54 ` Terje Bergström
2012-11-30 6:53 ` Thierry Reding
2012-11-29 9:10 ` [RFC,v2,1/8] " Mark Zhang
2012-12-10 10:28 ` Terje Bergström
2012-11-26 13:19 ` [RFC v2 2/8] video: tegra: Add syncpoint wait and interrupts Terje Bergstrom
2012-11-27 11:02 ` Sivaram Nair
2012-11-29 8:44 ` Thierry Reding
2012-11-29 10:39 ` Terje Bergström
2012-11-30 7:22 ` Thierry Reding
2012-11-30 7:41 ` Terje Bergström
2012-11-29 18:41 ` Stephen Warren
2012-11-30 7:23 ` Thierry Reding
2012-11-26 13:19 ` [RFC v2 3/8] video: tegra: host: Add channel and client support Terje Bergstrom
2012-11-29 10:01 ` [RFC,v2,3/8] " Mark Zhang
2012-11-29 10:46 ` Terje Bergström
2012-11-30 6:13 ` Mark Zhang
2012-11-29 10:04 ` [RFC v2 3/8] " Thierry Reding
2012-11-29 11:00 ` Terje Bergström
2012-11-30 7:46 ` Thierry Reding
2012-11-26 13:19 ` [RFC v2 4/8] video: tegra: Add debug support Terje Bergstrom
2012-11-26 13:19 ` [RFC v2 5/8] ARM: tegra: Add auxiliary data for nvhost Terje Bergstrom
2012-11-26 23:39 ` Stephen Warren
2012-11-27 6:33 ` Terje Bergström
2012-11-27 17:17 ` Stephen Warren
2012-11-26 13:19 ` [RFC v2 6/8] gpu: drm: tegra: Remove redundant host1x Terje Bergstrom
2012-12-05 8:33 ` Thierry Reding
2012-12-05 10:10 ` Terje Bergström
2012-12-05 11:13 ` Thierry Reding
2012-12-05 11:47 ` Terje Bergström
2012-12-05 12:02 ` Lucas Stach
2012-12-05 12:03 ` Daniel Vetter
2012-12-05 12:08 ` Daniel Vetter
2012-12-05 12:22 ` Thierry Reding
2012-12-05 12:31 ` Daniel Vetter
2012-12-05 13:28 ` Thierry Reding
2012-12-05 16:34 ` Daniel Vetter
2012-12-05 20:44 ` Thierry Reding
2012-12-05 12:04 ` Thierry Reding [this message]
2012-12-05 15:43 ` Terje Bergström
2012-12-10 11:42 ` Terje Bergström
2012-12-12 16:08 ` Thierry Reding
2012-12-12 16:56 ` Terje Bergström
2012-12-13 8:48 ` Terje Bergström
2012-12-13 8:57 ` Thierry Reding
2012-12-13 17:58 ` Stephen Warren
2012-12-13 20:32 ` Thierry Reding
2012-12-14 6:09 ` Terje Bergström
2012-12-14 16:21 ` Stephen Warren
2012-12-14 19:59 ` Terje Bergström
2012-12-16 12:16 ` Thierry Reding
2012-12-16 16:37 ` Terje Bergström
2012-12-17 20:55 ` Stephen Warren
2012-12-18 6:37 ` Terje Bergström
2012-12-20 9:17 ` Terje Bergström
2012-12-20 17:14 ` Stephen Warren
2012-12-20 17:46 ` Terje Bergström
2012-12-20 17:55 ` Stephen Warren
2012-12-20 18:01 ` Terje Bergström
2012-12-20 20:30 ` Thierry Reding
2012-12-20 21:34 ` Terje Bergström
2012-12-20 21:50 ` Thierry Reding
2012-12-20 22:29 ` Stephen Warren
2012-12-20 22:28 ` Stephen Warren
2012-12-21 6:31 ` Terje Bergström
2012-12-21 8:57 ` Arto Merilainen
2012-12-21 21:19 ` Stephen Warren
2013-01-02 5:41 ` Terje Bergström
2013-01-04 10:09 ` Terje Bergström
2013-01-04 20:25 ` Stephen Warren
2013-01-07 8:20 ` Terje Bergström
2013-01-07 17:07 ` Stephen Warren
2013-01-15 11:30 ` Thierry Reding
2013-01-15 11:41 ` Terje Bergström
2012-11-26 13:19 ` [RFC v2 7/8] gpu: drm: tegra: Prime support Terje Bergstrom
2012-11-26 13:19 ` [RFC v2 8/8] drm: tegra: Add gr2d device Terje Bergstrom
2012-11-26 21:59 ` Rob Clark
2012-11-26 22:15 ` Dave Airlie
2012-11-27 6:52 ` Terje Bergström
2012-11-27 7:33 ` Dave Airlie
2012-11-27 8:16 ` Terje Bergström
2012-11-27 8:32 ` Dave Airlie
2012-11-27 8:45 ` Terje Bergström
2012-11-27 10:22 ` Lucas Stach
2012-11-27 10:37 ` Thierry Reding
2012-11-27 11:31 ` Terje Bergström
2012-11-27 11:47 ` Lucas Stach
2012-11-27 12:59 ` Terje Bergström
2012-11-27 23:00 ` Dave Airlie
2012-11-28 13:17 ` Terje Bergström
2012-11-28 13:33 ` Lucas Stach
2012-11-28 13:57 ` Terje Bergström
2012-11-28 14:06 ` Lucas Stach
2012-11-28 14:45 ` Terje Bergström
2012-11-28 15:13 ` Lucas Stach
2012-11-28 16:23 ` Terje Bergström
2012-11-28 18:46 ` Lucas Stach
2012-11-29 8:17 ` Terje Bergström
2012-11-29 9:09 ` Lucas Stach
2012-11-29 12:14 ` Thierry Reding
2012-11-30 7:44 ` Terje Bergström
2012-11-30 7:53 ` Lucas Stach
2012-11-29 13:36 ` Terje Bergström
2012-11-28 16:24 ` Stephen Warren
2012-11-28 20:53 ` Thomas Hellstrom
2012-12-03 9:30 ` Mark Zhang
2012-12-03 9:40 ` Daniel Vetter
2012-12-04 1:49 ` Mark Zhang
2012-11-29 7:37 ` [RFC,v2,8/8] " Mark Zhang
2012-12-01 14:45 ` [RFC v2 0/8] Support for Tegra 2D hardware Thierry Reding
2012-12-01 17:08 ` Terje Bergström
2012-12-01 19:29 ` Thierry Reding
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