[Intel-gfx] [RFC] Runtime display PM for VLV/BYT

Ville Syrjälä ville.syrjala at linux.intel.com
Tue Oct 15 10:06:06 CEST 2013

On Mon, Oct 14, 2013 at 04:07:44PM -0700, Jesse Barnes wrote:
> This set adds bits needed for runtime power support, currently only
> lightly tested on VLV/BYT:
>   1) suspend/resume callbacks for different platforms
>   2) save/restore of display state across a power well toggle
>   3) get/put of display power well in critical places
> The TODO list still has a few items on it, and I'm looking for feedback:
>   1) sprinkle around some power well WARNs so we can catch things easily
>   2) add some tests using DPMS and NULL mode sets and comparing power
>      well state
>   3) better debugfs support for multiple wells
>   4) refcount of power well in debugfs (with ref holders?)
>   5) more testing - I think the load time ref is still busted here and
>      on HSW
>   6) convert HSW as well so DPMS will shut things down, not just mode
>      sets
> Thoughts or comments?

I'd also like to see what Imre cooked up, and then come up with some
grand unified design. Based on our discussions I think his power well
abstraction sounded somewhat nicer and more general.

Also your locking seems to be fubar in places (frobbing with sideband
while holding a spinlock). I think Imre converted the power wells to
use a mutex everywhere.

Or perhaps we just start with your stuff and Imre rebases his stuff on

Ville Syrjälä
Intel OTC

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