[Intel-gfx] [RFC PATCH 1/3] drm/915: Add private api for power well usage

Jesse Barnes jbarnes at virtuousgeek.org
Thu May 9 20:53:15 CEST 2013

On Thu, 9 May 2013 11:30:01 -0700
Jesse Barnes <jesse.barnes at intel.com> wrote:

> > The question is in which level we need power_well_*() controls.
> > If the initialization of HD-audio controller (e.g. PCI registers)
> > requires the power well on, hda_intel.c requires the calls, as this
> > patch does.  OTOH, if it's only about the HD-audio verbs, basically we
> > can push the power well calls into the codec driver,
> > i.e. patch_hdmi.c.  In the latter case, as David once suggested, we
> > can split the Haswell codec driver from patch_hdmi.c so that only the
> > new driver depends on i915.  
> I think it's needed for the HDMI related MMIO regs as well, but I don't
> have a platform to test and make sure.

Sorry, HD regs, not HDMI (though the power well is needed for those
too :).  AFAIK all the registers for interacting with HDMI audio on the
graphics device require the power well to be up in order to be accessed.

Jesse Barnes, Intel Open Source Technology Center

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