[Intel-gfx] [PATCH] drm: Disable all the possibles output/crtcs before entering KMS mode

[ykzhao]

On Sat, 2009-12-05 at 06:22 +0800, Rafał Miłecki wrote:
> 2009/12/4 Dave Airlie <airlied at redhat.com>:
> > On Fri, 2009-12-04 at 20:05 +0800, yakui.zhao at intel.com wrote:
> >> From: Zhao Yakui <yakui.zhao at intel.com>
> >>
> >> Disable all the possible outputs/crtcs before entering KMS mode.
> >
> > We need a bit more info than this for such a large change?
> >
> > At one point we wanted to do smooth startup for LVDS panels,
> > so that we read back the mode and avoided reconfiguring them
> > this sort of change would totally go against it.
> >
> > Also I thought Arjan wanted to avoid slowdowns on startup,
> > which I would expect this to add to.
> 
> We have something like drm_disable_unused_functions. Isn't that
> supposed to make what you introduce there? At least at KMS booting
> when we don't have encoders/crtcs/outputs configured it should work
> for that. Am I wrong?

Yes. Your are right. 

The main purpose of this function is to put all the outputs/crtcs into
the known state. In fact this function can also be called in course of
suspend/resume.

Before we have the encoder/crts/output configuration, the
drm_helper_disable_unused_functions can also put all the outputs/crtcs
into the known state. But after we build the connection between
encoder/crtcs/output, the function of
drm_helper_disable_unused_functions can only disable the unused
crtc/output.

Thanks.

>