Re: [PATCH 3/4] drm/fb-helper: Add module option to disable fbdev emulation

Daniel Vetter
2015-08-26T11:37:52Z

On Wed, Aug 26, 2015 at 01:34:58PM +0200, Daniel Vetter wrote:
> On Wed, Aug 26, 2015 at 02:14:37PM +0530, Archit Taneja wrote:
> >
> >
> > On 08/26/2015 10:42 AM, Archit Taneja wrote:
> > >
> > >
> > >On 08/25/2015 07:15 PM, Daniel Vetter wrote:
> > >>Faster than recompiling.
> > >>
> > >>Note that restore_fbdev_mode_unlocked is a bit special and the only
> > >>one which returns an error code when fbdev isn't there - i915 needs
> > >>that one to not fall over with some additional fbcon related restore
> > >>code. Everyone else just ignores the return value or only prints a
> > >>DRM_DEBUG level message.
> > >
> > >Reviewed-by:Archit Taneja <architt@codeaurora.org>
> >
> >
> > With the module param, and the drivers should see the following state(
> > based on the truth table below):
> >
> > module param | config option
> > true | true -> real helper funcs called, driver
> > allocated drm_fb_helper is correctly
> > populated.
> >
> > false | true -> real helper funcs called, but bailed
> > out early, driver allocated
> > drm_fb_helper is non-NULL, but we won't
> > end up using it.
>
> Hm I tried to give drivers the same semantics here as with the stub
> functions. Where did I screw up? The goal really was to match the end
> result for drivers ...

Note that at least for i915 we can't make it perfectly equal since i915
compiles out a few more things with FBDEV_EMULATION=n than just the stubs.
Long-term we might want to push some of that into helpers too perhaps.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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