Re: [PATCH 14/19] drm/i915: switch order of power domain init wrt. irq install

[Imre Deak <imre.deak@intel.com>]

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On Thu, 2014-02-20 at 11:48 -0800, Jesse Barnes wrote:
> On Tue, 18 Feb 2014 00:02:15 +0200
> Imre Deak <imre.deak@intel.com> wrote:
> 
> > On VLV at least the display IRQ register access and functionality
> > depends on its power well to be on, so move the power domain HW init
> > before we install the IRQs.
> > 
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_dma.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> > index 8177c17..f8f7a59 100644
> > --- a/drivers/gpu/drm/i915/i915_dma.c
> > +++ b/drivers/gpu/drm/i915/i915_dma.c
> > @@ -1321,12 +1321,12 @@ static int i915_load_modeset_init(struct drm_device *dev)
> >  	if (ret)
> >  		goto cleanup_vga_switcheroo;
> >  
> > +	intel_power_domains_init_hw(dev_priv);
> > +
> >  	ret = drm_irq_install(dev);
> >  	if (ret)
> >  		goto cleanup_gem_stolen;
> >  
> > -	intel_power_domains_init_hw(dev_priv);
> > -
> >  	/* Important: The output setup functions called by modeset_init need
> >  	 * working irqs for e.g. gmbus and dp aux transfers. */
> >  	intel_modeset_init(dev);
> 
> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> 
> That said, this was always one part of the PM code that confused me and
> caused some refcounts to get messed up last time I worked on it.
>
> I think it would be better to not treat init specially, and let the
> power wells get turned on and off through normal power well get/put
> calls during init and resume.

I agree this is the ideal way and we should move towards that. Atm, we
have intel_display_set_init_power() for init and resume which is not so
nice, but it should do the right thing.

> It's a bit noisy, power wise, but ultimately it might make for clearer
> code and one less special case.

Yep and also give some power saving.

--Imre

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