On Wed, Jan 17, 2024 at 01:12:49PM +0200, Ville Syrjälä wrote:
> On Wed, Jan 17, 2024 at 12:12:18PM +0200, Lisovskiy, Stanislav wrote:
> > On Fri, Jan 12, 2024 at 07:35:24PM +0200, Ville Syrjälä wrote:
> > > On Tue, Nov 28, 2023 at 10:37:53AM +0200, Stanislav Lisovskiy wrote:
> > > > We need that in order to force disable SAGV in next patch.
> > > > Also it is beneficial to separate that code, as in majority cases,
> > > > when SAGV is enabled, we don't even need those calculations.
> > > > Also we probably need to determine max PSF GV point as well, however
> > > > currently we don't do that when we disable SAGV, which might be
> > > > actually causing some issues in that case.
> > > > 
> > > > Signed-off-by: Stanislav Lisovskiy <[email protected]>
> > > > ---
> > > >  drivers/gpu/drm/i915/display/intel_bw.c | 82 ++++++++++++++++++++-----
> > > >  1 file changed, 65 insertions(+), 17 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_bw.c 
> > > > b/drivers/gpu/drm/i915/display/intel_bw.c
> > > > index 583cd2ebdf89..efd408e96e8a 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_bw.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_bw.c
> > > > @@ -805,6 +805,64 @@ intel_atomic_get_bw_state(struct 
> > > > intel_atomic_state *state)
> > > >         return to_intel_bw_state(bw_state);
> > > >  }
> > > >  
> > > > +static unsigned int icl_max_bw_qgv_point(struct drm_i915_private *i915,
> > > > +                                        int num_active_planes)
> > > > +{
> > > > +       unsigned int max_bw_point = 0;
> > > > +       unsigned int max_bw = 0;
> > > > +       unsigned int num_qgv_points = 
> > > > i915->display.bw.max[0].num_qgv_points;
> > > > +       int i;
> > > > +
> > > > +       for (i = 0; i < num_qgv_points; i++) {
> > > > +               unsigned int idx;
> > > > +               unsigned int max_data_rate;
> > > > +
> > > > +               if (DISPLAY_VER(i915) > 11)
> > > > +                       idx = tgl_max_bw_index(i915, num_active_planes, 
> > > > i);
> > > > +               else
> > > > +                       idx = icl_max_bw_index(i915, num_active_planes, 
> > > > i);
> > > > +
> > > > +               if (idx >= ARRAY_SIZE(i915->display.bw.max))
> > > > +                       continue;
> > > > +
> > > > +               max_data_rate = i915->display.bw.max[idx].deratedbw[i];
> > > 
> > > Looks like that that part could be extracted to a helper
> > > to be used by both codepaths (would be a natural counterpart
> > > to adl_psf_bw()).
> > > 
> > > > +
> > > > +               /*
> > > > +                * We need to know which qgv point gives us
> > > > +                * maximum bandwidth in order to disable SAGV
> > > > +                * if we find that we exceed SAGV block time
> > > > +                * with watermarks. By that moment we already
> > > > +                * have those, as it is calculated earlier in
> > > > +                * intel_atomic_check,
> > > > +                */
> > > > +               if (max_data_rate > max_bw) {
> > > > +                       max_bw_point = i;
> > > > +                       max_bw = max_data_rate;
> > > > +               }
> > > > +       }
> > > > +
> > > > +       return max_bw_point;
> > > > +}
> > > > +
> > > > +unsigned int icl_max_bw_psf_gv_point(struct drm_i915_private *i915)
> > > > +{
> > > > +       unsigned int num_psf_gv_points = 
> > > > i915->display.bw.max[0].num_psf_gv_points;
> > > > +       unsigned int max_bw = 0;
> > > > +       unsigned int max_bw_point = 0;
> > > > +       int i;
> > > > +
> > > > +       for (i = 0; i < num_psf_gv_points; i++) {
> > > > +               unsigned int max_data_rate = adl_psf_bw(i915, i);
> > > > +
> > > > +               if (max_data_rate > max_bw) {
> > > > +                       max_bw_point = i;
> > > > +                       max_bw = max_data_rate;
> > > > +               }
> > > > +       }
> > > > +
> > > > +       return max_bw_point;
> > > > +}
> > > > +
> > > >  static int mtl_find_qgv_points(struct drm_i915_private *i915,
> > > >                                unsigned int data_rate,
> > > >                                unsigned int num_active_planes,
> > > > @@ -882,8 +940,6 @@ static int icl_find_qgv_points(struct 
> > > > drm_i915_private *i915,
> > > >                                const struct intel_bw_state 
> > > > *old_bw_state,
> > > >                                struct intel_bw_state *new_bw_state)
> > > >  {
> > > > -       unsigned int max_bw_point = 0;
> > > > -       unsigned int max_bw = 0;
> > > >         unsigned int num_psf_gv_points = 
> > > > i915->display.bw.max[0].num_psf_gv_points;
> > > >         unsigned int num_qgv_points = 
> > > > i915->display.bw.max[0].num_qgv_points;
> > > >         u16 psf_points = 0;
> > > > @@ -909,18 +965,6 @@ static int icl_find_qgv_points(struct 
> > > > drm_i915_private *i915,
> > > >  
> > > >                 max_data_rate = i915->display.bw.max[idx].deratedbw[i];
> > > >  
> > > > -               /*
> > > > -                * We need to know which qgv point gives us
> > > > -                * maximum bandwidth in order to disable SAGV
> > > > -                * if we find that we exceed SAGV block time
> > > > -                * with watermarks. By that moment we already
> > > > -                * have those, as it is calculated earlier in
> > > > -                * intel_atomic_check,
> > > > -                */
> > > > -               if (max_data_rate > max_bw) {
> > > > -                       max_bw_point = i;
> > > > -                       max_bw = max_data_rate;
> > > > -               }
> > > >                 if (max_data_rate >= data_rate)
> > > >                         qgv_points |= BIT(i);
> > > >  
> > > > @@ -964,9 +1008,13 @@ static int icl_find_qgv_points(struct 
> > > > drm_i915_private *i915,
> > > >          * cause.
> > > >          */
> > > >         if (!intel_can_enable_sagv(i915, new_bw_state)) {
> > > > -               qgv_points = BIT(max_bw_point);
> > > > -               drm_dbg_kms(&i915->drm, "No SAGV, using single QGV 
> > > > point %d\n",
> > > > -                           max_bw_point);
> > > > +               unsigned int max_bw_qgv_point = 
> > > > icl_max_bw_qgv_point(i915, num_active_planes);
> > > > +               unsigned int max_bw_psf_gv_point = 
> > > > icl_max_bw_psf_gv_point(i915);
> > > > +
> > > > +               qgv_points = BIT(max_bw_qgv_point);
> > > > +               psf_points = BIT(max_bw_psf_gv_point);
> > > 
> > > We didn't restrict the PSF here previously.
> > 
> > Yep, but I really suspect we should. BSpec states that we should restrict 
> > all the GV points
> > except highest one, also that some PSF GV points aren't same or usable, 
> > depending on BW reqs.
> > So I would restrict that as well, in case if SAGV is off, just to be on 
> > safe side.
> 
> Pretty sure it's explicitly noted that PSF doesn't cause issues with
> latency and hence doesn't need this.
> 
> In any case, a change like this has no business being in a patch
> that's just supposed to refactor code.

Ok, lets drop this, until clarified.

Stan

> 
> -- 
> Ville Syrjälä
> Intel

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