[Intel-gfx] [PATCH] drm/i915: force full modeset if the connector is in DPMS OFF mode

Chris Wilson chris at chris-wilson.co.uk
Fri May 3 14:22:33 CEST 2013

On Fri, May 03, 2013 at 02:55:45PM +0300, Imre Deak wrote:
> On Fri, 2013-05-03 at 12:44 +0100, Chris Wilson wrote:
> > On Fri, May 03, 2013 at 02:22:09PM +0300, Imre Deak wrote:
> > > Currently the driver's assumed behavior for a modeset with an attached
> > > FB is that the corresponding connector will be switched to DPMS ON mode
> > > if it happened to be in DPMS OFF (or another power save mode). This
> > > wasn't enforced though if only the FB changed, everything else (format,
> > > connector etc.) remaining the same. In this case we only set the new FB
> > > base and left the connector in the old power save mode.
> > > 
> > > Fix this by forcing a full modeset whenever there is an attached FB and
> > > any affected connector is in a power save mode.
> > > 
> > > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > 
> > NAK. Papering over bugs, much?
> Ok. I posted this based on our IRC discussion where we seemed to agree
> that DPMS_ON is assumed already; just that it's not done consistently.
> That is if user space does a modeset now that ends up in a full modeset
> (lets say a new FB with different format) then the kernel will do a
> DPMS_ON. But if the new FB happens to be the same format then it won't.
> I thought this is inconsistent and should be fixed.
> Another way to make it consistent would be then to remove DPMS ON from
> the full modeset path..

Right, we have mentioned in the past that the conflation between DPMS
and modesetting is a more recent bug that is going to cause us even more
trouble later. I am not sure how we can fix that as UXA already makes
many bad assumptions.

Chris Wilson, Intel Open Source Technology Centre

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