Re: [Intel-gfx] [PATCH v28 4/6] drm/i915: Add TGL+ SAGV support

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

On Tue, May 12, 2020 at 04:38:21PM +0300, Ville Syrjälä wrote:
> On Tue, May 12, 2020 at 04:17:34PM +0300, Lisovskiy, Stanislav wrote:
> > On Tue, May 12, 2020 at 04:10:46PM +0300, Ville Syrjälä wrote:
> > > On Tue, May 12, 2020 at 03:52:27PM +0300, Lisovskiy, Stanislav wrote:
> > > > On Tue, May 12, 2020 at 03:03:26PM +0300, Ville Syrjälä wrote:
> > > > > On Thu, May 07, 2020 at 05:45:01PM +0300, Stanislav Lisovskiy wrote:
> > > > > > Starting from TGL we need to have a separate wm0
> > > > > > values for SAGV and non-SAGV which affects
> > > > > > how calculations are done.
> > > > > > 
> > > > > > v2: Remove long lines
> > > > > > v3: Removed COLOR_PLANE enum references
> > > > > > v4, v5, v6: Fixed rebase conflict
> > > > > > v7: - Removed skl_plane_wm_level accessor from skl_allocate_pipe_ddb(Ville)
> > > > > >     - Removed sagv_uv_wm0(Ville)
> > > > > >     - can_sagv->use_sagv_wm(Ville)
> > > > > > 
> > > > > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > > > > > ---
> > > > > >  drivers/gpu/drm/i915/display/intel_display.c  |   8 +-
> > > > > >  .../drm/i915/display/intel_display_types.h    |   2 +
> > > > > >  drivers/gpu/drm/i915/intel_pm.c               | 118 +++++++++++++++++-
> > > > > >  3 files changed, 121 insertions(+), 7 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > > > > > index fd6d63b03489..be5741cb7595 100644
> > > > > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > > > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > > > > @@ -13961,7 +13961,9 @@ static void verify_wm_state(struct intel_crtc *crtc,
> > > > > >  		/* Watermarks */
> > > > > >  		for (level = 0; level <= max_level; level++) {
> > > > > >  			if (skl_wm_level_equals(&hw_plane_wm->wm[level],
> > > > > > -						&sw_plane_wm->wm[level]))
> > > > > > +						&sw_plane_wm->wm[level]) ||
> > > > > > +			    (level == 0 && skl_wm_level_equals(&hw_plane_wm->wm[level],
> > > > > > +							       &sw_plane_wm->sagv_wm0)))
> > > > > >  				continue;
> > > > > >  
> > > > > >  			drm_err(&dev_priv->drm,
> > > > > > @@ -14016,7 +14018,9 @@ static void verify_wm_state(struct intel_crtc *crtc,
> > > > > >  		/* Watermarks */
> > > > > >  		for (level = 0; level <= max_level; level++) {
> > > > > >  			if (skl_wm_level_equals(&hw_plane_wm->wm[level],
> > > > > > -						&sw_plane_wm->wm[level]))
> > > > > > +						&sw_plane_wm->wm[level]) ||
> > > > > > +			    (level == 0 && skl_wm_level_equals(&hw_plane_wm->wm[level],
> > > > > > +							       &sw_plane_wm->sagv_wm0)))
> > > > > >  				continue;
> > > > > >  
> > > > > >  			drm_err(&dev_priv->drm,
> > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > > index 9488449e4b94..8cede29c9562 100644
> > > > > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > > @@ -688,11 +688,13 @@ struct skl_plane_wm {
> > > > > >  	struct skl_wm_level wm[8];
> > > > > >  	struct skl_wm_level uv_wm[8];
> > > > > >  	struct skl_wm_level trans_wm;
> > > > > > +	struct skl_wm_level sagv_wm0;
> > > > > >  	bool is_planar;
> > > > > >  };
> > > > > >  
> > > > > >  struct skl_pipe_wm {
> > > > > >  	struct skl_plane_wm planes[I915_MAX_PLANES];
> > > > > > +	bool use_sagv_wm;
> > > > > >  };
> > > > > >  
> > > > > >  enum vlv_wm_level {
> > > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > index db188efee21e..934a686342ad 100644
> > > > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > @@ -3863,25 +3863,35 @@ bool intel_can_enable_sagv(struct drm_i915_private *dev_priv,
> > > > > >  	return bw_state->pipe_sagv_reject == 0;
> > > > > >  }
> > > > > >  
> > > > > > +static bool
> > > > > > +tgl_crtc_can_enable_sagv(const struct intel_crtc_state *crtc_state);
> > > > > 
> > > > > Just put the function here instead of adding fwd decalrations.
> > > > > 
> > > > > > +
> > > > > >  static int intel_compute_sagv_mask(struct intel_atomic_state *state)
> > > > > >  {
> > > > > >  	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> > > > > >  	int ret;
> > > > > >  	struct intel_crtc *crtc;
> > > > > > -	const struct intel_crtc_state *new_crtc_state;
> > > > > > +	struct intel_crtc_state *new_crtc_state;
> > > > > >  	struct intel_bw_state *new_bw_state = NULL;
> > > > > >  	const struct intel_bw_state *old_bw_state = NULL;
> > > > > >  	int i;
> > > > > >  
> > > > > >  	for_each_new_intel_crtc_in_state(state, crtc,
> > > > > >  					 new_crtc_state, i) {
> > > > > > +		bool can_sagv;
> > > > > > +
> > > > > >  		new_bw_state = intel_atomic_get_bw_state(state);
> > > > > >  		if (IS_ERR(new_bw_state))
> > > > > >  			return PTR_ERR(new_bw_state);
> > > > > >  
> > > > > >  		old_bw_state = intel_atomic_get_old_bw_state(state);
> > > > > >  
> > > > > > -		if (skl_crtc_can_enable_sagv(new_crtc_state))
> > > > > > +		if (INTEL_GEN(dev_priv) >= 12)
> > > > > > +			can_sagv = tgl_crtc_can_enable_sagv(new_crtc_state);
> > > > > > +		else
> > > > > > +			can_sagv = skl_crtc_can_enable_sagv(new_crtc_state);
> > > > > > +
> > > > > > +		if (can_sagv)
> > > > > >  			new_bw_state->pipe_sagv_reject &= ~BIT(crtc->pipe);
> > > > > >  		else
> > > > > >  			new_bw_state->pipe_sagv_reject |= BIT(crtc->pipe);
> > > > > > @@ -3899,6 +3909,24 @@ static int intel_compute_sagv_mask(struct intel_atomic_state *state)
> > > > > >  			return ret;
> > > > > >  	}
> > > > > >  
> > > > > > +	for_each_new_intel_crtc_in_state(state, crtc,
> > > > > > +					 new_crtc_state, i) {
> > > > > > +		struct skl_pipe_wm *pipe_wm = &new_crtc_state->wm.skl.optimal;
> > > > > > +
> > > > > > +		/*
> > > > > > +		 * Due to drm limitation at commit state, when
> > > > > > +		 * changes are written the whole atomic state is
> > > > > > +		 * zeroed away => which prevents from using it,
> > > > > > +		 * so just sticking it into pipe wm state for
> > > > > > +		 * keeping it simple - anyway this is related to wm.
> > > > > > +		 * Proper way in ideal universe would be of course not
> > > > > > +		 * to lose parent atomic state object from child crtc_state,
> > > > > > +		 * and stick to OOP programming principles, which had been
> > > > > > +		 * scientifically proven to work.
> > > > > > +		 */
> > > > > 
> > > > > More ramblings. Just drop this comment too imo.
> > > > 
> > > > As I understand what is happening here is rather weird, so I thought 
> > > > commenting is good idea.
> > > 
> > > At least I have no idea what the comment is trying to say.
> > > I see nothing weird hapening here, we're just computing the
> > > state which is totally standard stuff.
> > 
> > Well I can remind, this is because there is no way to get parent state
> > from crtc_state, because of weird drm atomic behaviour which leaves us
> > with NULL parent state. So that we had to stick this boolean to some
> > place.
> > In normal code universe this wouldn't even be needed if we could
> > just get atomic state from crtc_state when we write wm in skl_write_plane_wm.
> 
> Didn't get that at all from the comment. It talked about zeroing some
> whole state which I took as 'memset(state, 0, sizeof(*state))'.
> As that is not what's going on I just got confused by the comment.
> 
> Now that I understand what this is about I think the comment
> (if we want to have one) should probably say something more like:
> "we store use_sagv_wm in the crtc state rather than relying on
>  the bw state since we have no convenient way to get at the
>  latter from the plane commit hooks (especially in the legacy
>  cursor case)".
> 
> > 
> > However probably OOP principles like parent-child hieararchy is not a thing
> > here. That what this comment was trying to say.
> > 
> > In normal OOP you can't destroy parent object _before_ destroying
> > child one.
> 
> There's no parent-child relationship between the crtc state and atomic
> state (which really shouldn't be called a state to begin with, rather
> it should be "transaction" or something along those lines).

In practice there is. crtc_state is being aggregated and contained as 
part of more general atomic state. That is exactly what parent-child
object relation is.
If you want to decouple those, this needs to be not aggregation but a reference,
i.e atomic state would not contain those state objects, but have a pointer
instead, but then you would not be using that container_of magic.

Stan

> 
> -- 
> Ville Syrjälä
> Intel
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx