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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