Re: [PATCH 0/3] drm/exynos: Allow module to be autoloaded

[Sjoerd Simons <sjoerd.simons@collabora.co.uk>]

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On Tue, 2014-07-29 at 14:38 +0900, Inki Dae wrote:
> On 2014년 07월 28일 23:45, Sjoerd Simons wrote:
> > Hey Inki,
> > 
> > On Mon, 2014-07-28 at 23:17 +0900, Inki Dae wrote:
> >> On 2014년 07월 28일 17:30, Sjoerd Simons wrote:
> >> Sorry for late,
> >>
> >> I don't see why Exynos drm driver should be auto-loaded module. I think
> >> all devices covered by Exynos drm framework are not hot-plugged. Maybe
> >> there is my missing point. So can you explain why Exynos drm driver
> >> should be auto-loaded module?
> > 
> > The background for this is that I'm building a distribution-style
> > multiplatform kernel, that is to say a kernel which can boot on a big
> > set of different ARM boards. As such, the intention is to keep the core
> > zImage as small as possible and essentially build things as far as
> > possible as loadable modules. So in a sense, all of the hardware is
> > "hotplugged", depending on which board the kernel is actually booted on!
> > 
> > For that use-case, exynosdrm needs to be able to build as a module
> > (which it already can!) and it needs the required meta-data for
> > userspace to know when it should be loaded. The latter is what my patch
> > adds. 
> 
> It seems that you want that module data of sub drivers are added by
> depmod to /lib/modules/KERNEL_VERSION/modules.xxxmap because some
> hot-plug system should use modules.xxxmap file to find the proper driver
> to load.

Yes. I would like the module to export its module alias information for
the subdrivers such that depmod can add it to its databases and the
normal module autoloading mechanisms work as intended. Note that in my
case, "some hot-plug" system is really just udev, not something
special..


> Ok, then does exynos drm driver is loaded well with your patches? 

It is indeed.

> My concern is that device_id of exynos drm core driver ,
> exynos_drm_drv.c, wouldn't be exported to userspace, which means that
> exynos drm subsystem aren't bound by component framework because most
> sub drivers except vidi are bound by component interfaces of exynos drm
> core: exynos drm drv is not device tree base driver.

This patchset doesn't change how that works. Really all it does is to
tell userspace which devices exynosdrm supports. From the kernel side of
things, there is no difference between the module being loaded based on
that information vs. it being loaded by hand.

-- 
Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Collabora Ltd.

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