Re: [Intel-gfx] [PATCH 02/14] drm/i915: Fix g4x cxsr enable condition

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Fri, Sep 17, 2021 at 03:32:51PM +0300, Ville Syrjälä wrote:
> On Thu, Sep 16, 2021 at 07:24:21PM +0300, Lisovskiy, Stanislav wrote:
> > On Fri, May 14, 2021 at 03:57:39PM +0300, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > The intention was to check whether the primary plane is enabled
> > > without any sprites planes being enabled. Instead we ended up checking
> > > whether just any one of the planes is enabled. g4x isn't vlv/chv and
> > > cxsr only works with the primary plane. Fix the check to examine the
> > > bitmask of active planes rather than the number of bits set in said
> > > bitmask.
> > > 
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_pm.c | 5 ++---
> > >  1 file changed, 2 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > > index 00a5fe424c5a..2fb496fbed43 100644
> > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > @@ -1376,8 +1376,7 @@ static int g4x_compute_pipe_wm(struct intel_crtc_state *crtc_state)
> > >  	struct intel_atomic_state *state =
> > >  		to_intel_atomic_state(crtc_state->uapi.state);
> > >  	struct g4x_wm_state *wm_state = &crtc_state->wm.g4x.optimal;
> > > -	int num_active_planes = hweight8(crtc_state->active_planes &
> > > -					 ~BIT(PLANE_CURSOR));
> > > +	u8 active_planes = crtc_state->active_planes & ~BIT(PLANE_CURSOR);
> > >  	const struct g4x_pipe_wm *raw;
> > >  	const struct intel_plane_state *old_plane_state;
> > >  	const struct intel_plane_state *new_plane_state;
> > > @@ -1417,7 +1416,7 @@ static int g4x_compute_pipe_wm(struct intel_crtc_state *crtc_state)
> > >  	wm_state->sr.cursor = raw->plane[PLANE_CURSOR];
> > >  	wm_state->sr.fbc = raw->fbc;
> > >  
> > > -	wm_state->cxsr = num_active_planes == BIT(PLANE_PRIMARY);
> > > +	wm_state->cxsr = active_planes == BIT(PLANE_PRIMARY);
> > 
> > Shouldn't this be "active_planes & BIT(PLANE_PRIMARY)" as we might
> > have other non-cursor planes enabled, which will then fail or am I missing something?
> 
> CxSR is possible only when the primary plane is enabled and the
> sprite plane is disabled.

Ok, that explains.

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

> 
> -- 
> Ville Syrjälä
> Intel