From: Thierry Reding <thierry.reding@gmail.com>
To: "Matwey V. Kornilov" <matwey.kornilov@gmail.com>
Cc: kyungmin.park@samsung.com, sw0312.kim@samsung.com,
dri-devel@lists.freedesktop.org
Subject: Re: exynos-drm registration: infinite loop
Date: Wed, 5 Nov 2014 15:38:14 +0100 [thread overview]
Message-ID: <20141105143813.GA24353@ulmo> (raw)
In-Reply-To: <CAJs94EY48vVwqCFiVEJkFgwsP+Pu7hKDQVDGURK0qxBw2oBWNw@mail.gmail.com>
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On Tue, Nov 04, 2014 at 09:18:46PM +0400, Matwey V. Kornilov wrote:
> Hi,
>
> I run 3.18-rc3 kernel on BeagleBone Black. It doesn't have Exynos DRM
> of course, but I run multi-platform kernel where CONFIG_DRM_EXYNOS is
> set to 'y'.
> The issue here is that the platform probe/init goes to infinite loop
> as the following:
>
> [ 5.717343] platform exynos-drm: Driver exynos-drm requests probe deferral
> [ 5.726848] exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
> [ 5.734700] platform exynos-drm: Driver exynos-drm requests probe deferral
> [ 5.744044] exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
> [ 5.752010] platform exynos-drm: Driver exynos-drm requests probe deferral
> [ 5.761377] exynos-drm-ipp exynos-drm-ipp: drm ipp registered successfully.
> [ 5.769291] platform exynos-drm: Driver exynos-drm requests probe deferral
>
> It is quite unexpectable behavior. I would expect that the exynos-drm
> failed to initialize with 'no device' error.
>
> See also for the reference: https://bugzilla.kernel.org/show_bug.cgi?id=87691
The reason for this seems to be that Exynos DRM instantiates a dummy
device that it can bind to (see exynos_drm_init()). Now this code is
executed unconditonally, so the device will be created whether or not
the kernel/module runs on an Exynos SoC. The driver should really bind
to some real device rather than instantiating a dummy. Or if it must
bind to a dummy then the code needs to at least check that it's running
on an Exynos SoC before instantiating the dummy.
Thierry
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next prev parent reply other threads:[~2014-11-05 14:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 17:18 exynos-drm registration: infinite loop Matwey V. Kornilov
2014-11-05 14:38 ` Thierry Reding [this message]
2014-11-05 16:47 ` Matwey V. Kornilov
2014-11-06 6:23 ` Inki Dae
2014-11-06 8:03 ` Andrzej Hajda
2014-11-06 8:45 ` Inki Dae
2014-11-06 8:49 ` Matwey V. Kornilov
2014-11-06 9:03 ` Inki Dae
2014-11-06 9:29 ` Thierry Reding
2014-11-06 9:51 ` Inki Dae
2014-11-06 5:45 ` Inki Dae
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