Re: [PATCH 2/4] drm/i915: Use old mbus_join value when increasing CDCLK

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

On Mon, Mar 25, 2024 at 07:01:48PM +0200, Ville Syrjälä wrote:
> On Mon, Mar 25, 2024 at 06:55:21PM +0200, Lisovskiy, Stanislav wrote:
> > On Mon, Mar 25, 2024 at 04:30:14PM +0200, Ville Syrjälä wrote:
> > > On Mon, Mar 25, 2024 at 01:23:27PM +0200, Stanislav Lisovskiy wrote:
> > > > In order to make sure we are not breaking the proper sequence
> > > > lets to updates step by step and don't change MBUS join value
> > > > during MDCLK/CDCLK programming stage.
> > > > MBUS join programming would be taken care by pre/post ddb hooks.
> > > > 
> > > > v2: - Reworded comment about using old mbus_join value in
> > > >       intel_set_cdclk(Ville Syrjälä)
> > > > 
> > > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/display/intel_cdclk.c | 12 +++++++++++-
> > > >  1 file changed, 11 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> > > > index 31aaa9780dfcf..c7813d433c424 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> > > > @@ -2611,9 +2611,19 @@ intel_set_cdclk_pre_plane_update(struct intel_atomic_state *state)
> > > >  
> > > >  	if (pipe == INVALID_PIPE ||
> > > >  	    old_cdclk_state->actual.cdclk <= new_cdclk_state->actual.cdclk) {
> > > > +		struct intel_cdclk_config cdclk_config;
> > > > +
> > > >  		drm_WARN_ON(&i915->drm, !new_cdclk_state->base.changed);
> > > >  
> > > > -		intel_set_cdclk(i915, &new_cdclk_state->actual, pipe);
> > > > +		/*
> > > > +		 * By this hack we want to prevent mbus_join to be changed
> > > > +		 * beforehand
> > > 
> > > That sentence is still confusing.
> > 
> > Write it yourself then. I'm not going to rephrase it anymore.
> 
> You didn't rephrase it at all AFAIK.
> 
> Something like
> "MBUS joining will be changed later by
>  intel_dbuf_mbus_{pre,post}_ddb_update(), thus
>  keep using the old joined_mbus state during cdclk
>  programming to match the actual hardware state."

Basically my comment says exactly same stuff but with other
words, i.e preventing changing mbus join value beforehand,
until intel_dbuf_mbus_post_ddb_update takes care of that.

> 
> > 
> > > 
> > > > - we will take care of this later in
> > > > +		 * intel_dbuf_mbus_post_ddb_update
> > > > +		 */
> > > > +		cdclk_config = new_cdclk_state->actual;
> > > > +		cdclk_config.joined_mbus = old_cdclk_state->actual.joined_mbus;
> > > > +
> > > > +		intel_set_cdclk(i915, &cdclk_config, pipe);
> > > >  	}
> > > >  }
> > > >  
> > > > -- 
> > > > 2.37.3
> > > 
> > > -- 
> > > Ville Syrjälä
> > > Intel
> 
> -- 
> Ville Syrjälä
> Intel