2014-11-06 11:45 GMT+03:00 Inki Dae <inki.dae at samsung.com>: > On 2014ë 11ì 06ì¼ 17:03, Andrzej Hajda wrote: >> On 11/06/2014 07:23 AM, Inki Dae wrote: >>> On 2014ë 11ì 05ì¼ 23:38, Thierry Reding wrote: >>>> 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. >>>> >>> >>> Right, I also think the problem is because we use a dummay device for >>> Exynos drm. As you mentioned, this device can always be bound as long as >>> Exynos drm driver is enabled even without real device. So this issue >>> gives us that we need super device node again. Actually, I had already >>> tried the use of the super device node like below for Exynos drm but >>> other Samsung guys didn't want to use it. >>> http://lists.freedesktop.org/archives/dri-devel/2014-April/056618.html >>> >>> I think now we have the reason that we should use super device node so I >>> will try to support the super device for Exynos drm like other ARM drm >>> drivers did. However, for this, I'd like to listen to other opinions >>> for a while before that. >> >> It is enough to check if there are platform devices compatible with >> drivers registered by exynos_drm_dev. >> > > Yes, we can do it simply. However, I'm not still clear to handle these > issues in this manner because if we use the super device which is the > most generic way then Exynos drm can have real device node so we don't > need such exception codes anymore. And with the super device, I'm not > sure whether there are other issues or not we can face but it would be > enough to consider only generic ways. > > Anyway, I will decide how to handle Exynos drm device after listening to > more other opinions.
However, what is about CONFIG_DRM_EXYNOS = 'm' ? I suppose that the super device and the appropriate record in dts will make alias and auto-load work. > > Thanks, > Inki Dae > >> Regards >> Andrzej >> >>> >>> Thanks, >>> Inki Dae >>> >>>> Thierry >>>> >>>> >>>> >>>> _______________________________________________ >>>> dri-devel mailing list >>>> dri-devel at lists.freedesktop.org >>>> http://lists.freedesktop.org/mailman/listinfo/dri-devel >>>> >>> >>> _______________________________________________ >>> dri-devel mailing list >>> dri-devel at lists.freedesktop.org >>> http://lists.freedesktop.org/mailman/listinfo/dri-devel >>> >> >> > -- With best regards, Matwey V. Kornilov http://blog.matwey.name xmpp://0x2207 at jabber.ru
