[Intel-gfx] [RFC 04/15] drm/i915: Add headers for non-HDAudio HDMI interface

[Ville Syrjälä]

On Mon, Mar 14, 2016 at 05:21:54PM +0200, Ville Syrjälä wrote:
> On Mon, Mar 14, 2016 at 10:13:58AM -0500, Pierre-Louis Bossart wrote:
> > On 3/11/16 1:09 PM, Ville Syrjälä wrote:
> > > On Fri, Mar 11, 2016 at 11:27:13AM -0600, Pierre-Louis Bossart wrote:
> > >> Thanks for the review Ville
> > >>
> > >> [snip]
> > >>
> > >>> Kinda hard to see where everything gets used due to the way the patches
> > >>> are split up.
> > >>
> > >> Yes, it's far from great...
> > >>
> > >>> At least the hotplug/mode change events are not needed. We only have the
> > >>> two points where i915 should inform the audio driver about this stuff,
> > >>> and those are the intel_audio_code_enable/disable(). For that we
> > >>> already have the .pin_eld_notify() hook.
> > >>>
> > >>> The interrupt stuff should mostly vanish from i915 with the subdevice
> > >>> approach. As in i915 would just call the interrupt handler of the audio
> > >>> driver based on the LPE bits in IIR, and the audio driver can then do
> > >>> whatever it wants based on its own status register.
> > >>
> > >> Are you saying that the subdevice would provide a read/write interface
> > >> for the audio driver to look at display registers, and the i915 driver
> > >> would only provide a notification interface (EDID and interrupts) to the
> > >> audio driver?
> > >
> > > The audio driver would simply ioremap the appropriate range of
> > > registers itself.
> > >
> > >> If yes, would there be two component framework links, one between
> > >> i915/audio driver and one between subdevice/audio driver.
> > >
> > > Yeah sort of. i915 registers the platform device for the audio, the
> > > audio driver can then bind to the device via the platform driver .probe
> > > callback. It can then register with the audio component stuff at some
> > > point to get the relevant notifications on the display state. When
> > > i915 gets unloaded we remove the platform device, at which point the
> > > audio driver's platform driver .remove() callback gets invoked and
> > > it should unregister/cleanup everything.
> > 
> > we don't want to expose this interface when HDAudio is present and 
> > enabled so we would need to add a test for this.
> > Also it looks like you want the creation of the platform device done in 
> > i915, we were thinking of doing this as part of the audio drivers but in 
> > the end this looks equivalent. In both cases we would end-up ignoring 
> > the HAD022A8 HID and not use acpi for this extension
> 
> Well, if you have a device you can hang off from then i915 should need
> to register it I suppose. Though that would make the interrupt
> forwarding perhaps less nice. There's also the suspend/resume order
> dependency to deal with if there's no parent/child relationship between
> the devices.

Oh and I suppose you'd end up ioremapping part of the pci dev2 mmio bar
to get at the registers, which would look a bit funkly at least.

> 
> > 
> > > I just tried to frob around with the VED code a bit, and got it to load
> > > at least. It's not quite happy about reloading i915 while the ipvr
> > > driver was loaded though. Not sure what's going on there, but I do
> > > think this approach should work. So the VED patch could serve as a
> > > decent enough model to follow.
> > >
> 
> -- 
> Ville Syrjälä
> Intel OTC
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-- 
Ville Syrjälä
Intel OTC