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

[Pandiyan, Dhinakaran]

On Mon, 2017-09-11 at 16:33 +0300, Ville Syrjälä wrote:
> 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.
> 
Thanks, do you see any potential problems patch with Patch 2/2?