[PATCH v2] drm/dp/mst: Sideband message transaction to power up/down nodes

[Ville Syrjälä]

On Wed, Sep 06, 2017 at 05:14:58PM -0700, Dhinakaran Pandiyan wrote:
> The POWER_DOWN_PHY and POWER_UP_PHY sideband message transactions allow
> the source to reqest any node in a mst path or a whole path to be
> powered down or up. This allows drivers to target a specific sink in the
> MST topology, an improvement over just power managing the imediate
> downstream device. Secondly, since the request-reply protocol waits for an
> ACK, we can be sure that a downstream sink has enough time to respond to a
> power up/down request.

I was a bit worried how this handles multiple streams going through
the same MST device, but looks like the spec has accounted for this
by having the device skip the D3 if any active streams are present.

I guess that also means we have to do this after we've turned off the
stream, assuming we want things actually reach D3. Looks like that does
match our current order of things.

Pushed this one to drm-misc-next. Thanks for the patch and review.

-- 
Ville Syrjälä
Intel OTC