Re: [PATCH] drm/i915/psr: Implment WA to help reach PC10

["Hogander, Jouni" <jouni.hogander@intel.com>]

On Mon, 2024-09-02 at 10:01 +0000, Kandpal, Suraj wrote:
> 
> 
> > -----Original Message-----
> > From: Hogander, Jouni <jouni.hogander@intel.com>
> > Sent: Monday, September 2, 2024 3:07 PM
> > To: Kandpal, Suraj <suraj.kandpal@intel.com>; intel-
> > gfx@lists.freedesktop.org
> > Cc: Shankar, Uma <uma.shankar@intel.com>
> > Subject: Re: [PATCH] drm/i915/psr: Implment WA to help reach PC10
> > 
> > On Mon, 2024-09-02 at 10:32 +0530, Suraj Kandpal wrote:
> > > To reach PC10 when PKG_C_LATENCY is configure we must do the
> > following
> > > things
> > > 1) Enter PSR1 only when delayed_vblank < 6 lines and DC5 can be
> > > entered
> > > 2) Allow PSR2 deep sleep when DC5 can be entered
> > > 3) DC5 can be entered when all transocoder have either PSR1, PSR2
> > > or
> > > eDP 1.5 PR ALPM enabled and VBI is disabled and flips and pushes
> > > are
> > > not happening.
> > > 
> > > --v2
> > > -Switch condition and do an early return [Jani] -Do some checks
> > > in
> > > compute_config [Jani] -Do not use register reads as a method of
> > > checking states for DPKGC or delayed vblank [Jani] -Use another
> > > way to
> > > see is vblank interrupts are disabled or not [Jani]
> > > 
> > > --v3
> > > -Use has_psr to check if psr can be enabled or not for dc5_entry
> > > cond
> > > [Uma] -Move the dc5 entry computation to psr_compute_config
> > > [Jouni]
> > > -No need to change sequence of enabled and activate, so dont make
> > > hsw_psr1_activate return anything [Jouni] -Use has_psr to stop
> > > psr1
> > > activation [Jouni] -Use lineage no. in WA -Add the display ver
> > > restrictions for WA
> > > 
> > > WA: 22019444797
> > > Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> > > ---
> > >  .../drm/i915/display/intel_display_types.h    |  2 +
> > >  drivers/gpu/drm/i915/display/intel_psr.c      | 96
> > > ++++++++++++++++++-
> > >  2 files changed, 97 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > index 868ff8976ed9..5395c1ecde7f 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > @@ -1717,6 +1717,8 @@ struct intel_psr {
> > >         bool sink_support;
> > >         bool source_support;
> > >         bool enabled;
> > > +       bool is_dpkgc_configured;
> > > +       bool is_dc5_entry_possible;
> > >         bool paused;
> > >         enum pipe pipe;
> > >         enum transcoder transcoder;
> > > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > > b/drivers/gpu/drm/i915/display/intel_psr.c
> > > index 257526362b39..1faec76eac32 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > > @@ -870,6 +870,69 @@ static u8 psr_compute_idle_frames(struct
> > intel_dp
> > > *intel_dp)
> > >         return idle_frames;
> > >  }
> > > 
> > > +static bool intel_psr_check_delayed_vblank_limit(struct
> > > intel_crtc_state *crtc_state)
> > 
> > You could add some context here in the name. This is somehow
> > telling it's
> > some generic delayed vblank limit while it is actually limit for
> > this
> > workaround.
> 
> Sure will fix in next revision
> How about something like check_wa_delayed_vblank()
> 
> > 
> > > +{
> > > +       struct drm_display_mode *adjusted_mode = &crtc_state-
> > > > hw.adjusted_mode;
> > > +
> > > +       return (adjusted_mode->crtc_vblank_start - adjusted_mode-
> > > > crtc_vdisplay) >= 6;
> > > +}
> > > +
> > > +/*
> > > + * PKG_C_LATENCY is configured only when DISPLAY_VER >= 20 and
> > > + * VRR is not enabled
> > > + */
> > > +static bool intel_psr_is_dpkgc_configured(struct
> > > drm_i915_private
> > > *i915)
> > > +{
> > > +       struct intel_crtc *intel_crtc;
> > > +
> > > +       if (DISPLAY_VER(i915) < 20)
> > > +               return false;
> > > +
> > > +       for_each_intel_crtc(&i915->drm, intel_crtc) {
> > > +               struct intel_crtc_state *crtc_state;
> > > +
> > > +               if (!intel_crtc->active)
> > > +                       continue;
> > > +
> > > +               crtc_state = intel_crtc->config;
> > > +
> > > +               if (crtc_state->vrr.enable)
> > > +                       return false;
> > > +       }
> > > +
> > > +       return true;
> > > +}
> > > +
> > > +/*
> > > + * DC5 entry is only possible if vblank interrupt is disabled
> > > + * and either psr1, psr2, edp 1.5 pr alpm is enabled on all
> > > + * enabled encoders.
> > > + */
> > > +static bool
> > > +intel_psr_is_dc5_entry_possible(struct drm_i915_private *i915,
> > > +                               struct intel_crtc_state
> > > *crtc_state) {
> > > +       struct intel_crtc *intel_crtc;
> > > +
> > > +       if (!(crtc_state->has_psr || crtc_state->has_sel_update))
> > > +               return false;
> > 
> > Currently this is not returning for DP2.1 PR. This would better
> > match with
> > comment above:
> > 
> > if (!crtc_state->has_psr || !intel_dp_is_edp(intel_dp))
> >     return false;
> > 
> > Still "_all_ enabled encoders" is not handled...
> > 
> 
> How about in the below loop I add a encoder loop that checks if
> intel_dp_is_edp
> If the encoder is active and the psr check is taken care of by
> checking crtc_state->has_psr ?
> Previously I used to check if psr->enabled but since this is now
> called in psr compute config I only have has_psr to check
> If psr can be enabled on that encoder .

Loop idea is ok. Also crtc_state->has_psr. Shouldn't you also handle
non-edp as well? If there is any non-edp encoder active I think dc5
will be blocked? 

BR,

Jouni Högander

> 
> Regards,
> Suraj Kandpal
> > BR,
> > 
> > Jouni Högander
> > 
> > > +
> > > +       for_each_intel_crtc(&i915->drm, intel_crtc) {
> > > +               struct drm_crtc *crtc = &intel_crtc->base;
> > > +               struct drm_vblank_crtc *vblank;
> > > +
> > > +               if (!intel_crtc->active)
> > > +                       continue;
> > > +
> > > +               vblank = drm_crtc_vblank_crtc(crtc);
> > > +
> > > +               if (vblank->enabled)
> > > +                       return false;
> > > +       }
> > > +
> > > +       return true;
> > > +}
> > > +
> > >  static void hsw_activate_psr1(struct intel_dp *intel_dp)
> > >  {
> > >         struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > > @@
> > > -980,7 +1043,11 @@ static void hsw_activate_psr2(struct intel_dp
> > > *intel_dp)
> > >         u32 val = EDP_PSR2_ENABLE;
> > >         u32 psr_val = 0;
> > > 
> > > -       val |=
> > > EDP_PSR2_IDLE_FRAMES(psr_compute_idle_frames(intel_dp));
> > > +       /* Wa_22019444797 */
> > > +       if (DISPLAY_VER(dev_priv) != 20 ||
> > > +           (intel_dp->psr.is_dpkgc_configured &&
> > > +            intel_dp->psr.is_dc5_entry_possible))
> > > +               val |=
> > > EDP_PSR2_IDLE_FRAMES(psr_compute_idle_frames(intel_dp));
> > > 
> > >         if (DISPLAY_VER(dev_priv) < 14 &&
> > > !IS_ALDERLAKE_P(dev_priv))
> > >                 val |= EDP_SU_TRACK_ENABLE; @@ -1595,6 +1662,32
> > > @@
> > > _panel_replay_compute_config(struct intel_dp *intel_dp,
> > >         return true;
> > >  }
> > > 
> > > +static void wa_22019444797(struct intel_dp *intel_dp,
> > > +                          struct intel_crtc_state *crtc_state) {
> > > +       struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > > +
> > > +       if (DISPLAY_VER(i915) != 20)
> > > +               return;
> > > +
> > > +       intel_dp->psr.is_dpkgc_configured =
> > > +               intel_psr_is_dpkgc_configured(i915);
> > > +       intel_dp->psr.is_dc5_entry_possible =
> > > +               intel_psr_is_dc5_entry_possible(i915,
> > > crtc_state);
> > > +
> > > +       /* PSR2 not handled here. Wa not needed for Panel Replay
> > > */
> > > +       if (crtc_state->has_sel_update || crtc_state-
> > > > has_panel_replay)
> > > +               return;
> > > +
> > > +       if (intel_dp->psr.is_dpkgc_configured &&
> > > +           (intel_psr_check_delayed_vblank_limit(crtc_state) ||
> > > +            intel_dp->psr.is_dc5_entry_possible)) {
> > > +               drm_dbg_kms(&i915->drm,
> > > +                           "PSR1 not enabled as it doesn't meet
> > > requirements of WA: 22019444797\n");
> > > +               crtc_state->has_psr = false;
> > > +       }
> > > +}
> > > +
> > >  void intel_psr_compute_config(struct intel_dp *intel_dp,
> > >                               struct intel_crtc_state
> > > *crtc_state,
> > >                               struct drm_connector_state
> > > *conn_state)
> > > @@ -1641,6 +1734,7 @@ void intel_psr_compute_config(struct
> > > intel_dp
> > > *intel_dp,
> > >                 return;
> > > 
> > >         crtc_state->has_sel_update =
> > > intel_sel_update_config_valid(intel_dp, crtc_state);
> > > +       wa_22019444797(intel_dp, crtc_state);
> > >  }
> > > 
> > >  void intel_psr_get_config(struct intel_encoder *encoder,
>