Re: [PATCH 2/2] drm/i915/psr: Implment WA to help reach PC10

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

On Fri, 2024-08-23 at 09:49 +0000, Kandpal, Suraj wrote:
> 
> 
> > -----Original Message-----
> > From: Hogander, Jouni <jouni.hogander@intel.com>
> > Sent: Friday, August 23, 2024 12:51 PM
> > To: Kandpal, Suraj <suraj.kandpal@intel.com>; intel-
> > gfx@lists.freedesktop.org
> > Cc: Murthy, Arun R <arun.r.murthy@intel.com>; Manna, Animesh
> > <animesh.manna@intel.com>; jani.nikula@linux.intel.com
> > Subject: Re: [PATCH 2/2] drm/i915/psr: Implment WA to help reach
> > PC10
> > 
> > On Fri, 2024-08-23 at 06:18 +0000, Kandpal, Suraj wrote:
> > > 
> > > 
> > > > -----Original Message-----
> > > > From: Hogander, Jouni <jouni.hogander@intel.com>
> > > > Sent: Friday, August 23, 2024 10:54 AM
> > > > To: Kandpal, Suraj <suraj.kandpal@intel.com>;
> > > > intel-gfx@lists.freedesktop.org
> > > > Cc: Murthy, Arun R <arun.r.murthy@intel.com>; Manna, Animesh
> > > > <animesh.manna@intel.com>; jani.nikula@linux.intel.com
> > > > Subject: Re: [PATCH 2/2] drm/i915/psr: Implment WA to help
> > > > reach
> > > > PC10
> > > > 
> > > > On Fri, 2024-08-23 at 04:54 +0000, Kandpal, Suraj wrote:
> > > > > 
> > > > > 
> > > > > > -----Original Message-----
> > > > > > From: Hogander, Jouni <jouni.hogander@intel.com>
> > > > > > Sent: Thursday, August 22, 2024 2:16 PM
> > > > > > To: Kandpal, Suraj <suraj.kandpal@intel.com>; intel-
> > > > > > gfx@lists.freedesktop.org
> > > > > > Cc: Murthy, Arun R <arun.r.murthy@intel.com>; Manna,
> > > > > > Animesh
> > > > > > <animesh.manna@intel.com>; jani.nikula@linux.intel.com
> > > > > > Subject: Re: [PATCH 2/2] drm/i915/psr: Implment WA to help
> > > > > > reach
> > > > > > PC10
> > > > > > 
> > > > > > On Wed, 2024-06-19 at 10:07 +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]
> > > > > > > 
> > > > > > > WA: 16023497226
> > > > > > > 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      | 82
> > > > > > > ++++++++++++++++++-
> > > > > > >  2 files changed, 83 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 46b3cbeb4a82..031f8e889b65 100644
> > > > > > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > > > > @@ -1708,6 +1708,8 @@ struct intel_psr {
> > > > > > >         bool sink_support;
> > > > > > >         bool source_support;
> > > > > > >         bool enabled;
> > > > > > > +       bool delayed_vblank;
> > > > > > > +       bool is_dpkgc_configured;
> > > > > > >         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 080bf5e51148..4ddea6737386 100644
> > > > > > > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > > > > > > @@ -808,6 +808,73 @@ 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)
> > > > > > > +{
> > > > > > > +       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 *intel_crtc;
> > > > > > > +
> > > > > > > +       for_each_intel_crtc(&i915->drm, intel_crtc) {
> > > > > > > +               struct intel_encoder *encoder;
> > > > > > > +               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;
> > > > > > > +
> > > > > > > +               for_each_encoder_on_crtc(&i915->drm,
> > > > > > > crtc,
> > > > > > > encoder) {
> > > > > > > +                       struct intel_dp *intel_dp =
> > > > > > > enc_to_intel_dp(encoder);
> > > > > > > +                       struct intel_psr *psr =
> > > > > > > &intel_dp-
> > > > > > > > psr;
> > > > > > > +
> > > > > > > +                       if (!psr->enabled)
> > > > > > > +                               return false;
> > > > > > > +               }
> > > > > > > +       }
> > > > > > > +
> > > > > > > +       return true;
> > > > > > > +}
> > > > > > > +
> > > > > > >  static bool hsw_activate_psr1(struct intel_dp *intel_dp)
> > > > > > >  {
> > > > > > >         struct drm_i915_private *dev_priv =
> > > > > > > dp_to_i915(intel_dp); @@
> > > > > > > -815,6 +882,14 @@ static bool hsw_activate_psr1(struct
> > > > > > > intel_dp
> > > > > > > *intel_dp)
> > > > > > >         u32 max_sleep_time = 0x1f;
> > > > > > >         u32 val = EDP_PSR_ENABLE;
> > > > > > > 
> > > > > > > +       /* WA: 16023497226*/
> > > > > > > +       if (intel_dp->psr.is_dpkgc_configured &&
> > > > > > > +           (intel_dp->psr.delayed_vblank ||
> > > > > > > intel_psr_is_dc5_entry_possible(dev_priv))) {
> > > > > > > +               drm_dbg_kms(&dev_priv->drm,
> > > > > > > +                           "PSR1 not activated as it
> > > > > > > doesn't
> > > > > > > meet
> > > > > > > requirements of WA:16023497226\n");
> > > > > > > +               return false;
> > > > > > > +       }
> > > > > > > +
> > > > > > 
> > > > > > I would recommend doing this in intel_psr_compute_config as
> > > > > > a
> > > > > > last step and drop patch 1. Doing it this way would be
> > > > > > safer as
> > > > > > it's not opening new sequence/state where psr.enabled =
> > > > > > true and
> > > > > > psr.active = false after intel_psr_enable_locked.
> > > > > 
> > > > > The reason for this was I wanted to disable only psr1 based
> > > > > on if
> > > > > dc5
> > > > > entry is possible or not.
> > > > > Even if I call the dc5_entry_is_possible function from
> > > > > compute_config and save it in the intel_psr state we would
> > > > > still
> > > > > end up with the seq psr.enabled = true and psr.active = false
> > > > > unless you see a param which will only activate psr2 and not
> > > > > psr1
> > > > > in such scenario ?
> > > > > 
> > > > 
> > > > I was thinking doing it like this:
> > > > 
> > > > +static void wa_16023497226(struct intel_crtc_state *
> > > > 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_dp->psr.delayed_vblank ||
> > > > +           intel_psr_is_dc5_entry_possible(dev_priv))) {
> > > > +               drm_dbg_kms(&dev_priv->drm,
> > > > +                           "PSR1 not enabled as it doesn't
> > > > meet
> > > > +                          requirements of WA:16023497226\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) @@ -
> > > > 1635,6 +1651,8 @@ 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_16023497226(crtc_state);
> > > >  }
> > > > 
> > > >  void intel_psr_get_config(struct intel_encoder *encoder,
> > > > 
> > > > Do you see this would be possible? Current PSR2 handling in
> > > > your
> > > > patches is ok to me.
> > > 
> > > Even if has_psr as false I see that hsw_psr1_activate can be
> > > invoked
> > > since there is No real check stopping it from getting activated
> > > 
> > > /* psr1, psr2 and panel-replay are mutually exclusive.*/
> > >         if (intel_dp->psr.panel_replay_enabled)
> > >                 dg2_activate_panel_replay(intel_dp);
> > >         else if (intel_dp->psr.sel_update_enabled)
> > >                 hsw_activate_psr2(intel_dp);
> > >         else
> > >                 ret = hsw_activate_psr1(intel_dp);
> > > 
> > > so if it isn't psr2 or panel replay we will activate psr1 do we
> > > need
> > > to add an else if statement here in that case.
> > 
> > No. That is taken care in caller of intel_psr_enable_locked:
> > 
> 
> Wouldn’t this stop us from enabling psr2 when could have been
> enabled?

No.

If you do it like in my example has_psr is cleared due to
wa_16023497226 only for PSR1. I.e when crtc_state->has_psr == true &&
crtc_state->has_sel_update == false && crtc_state->has_panel_replay ==
false. See  has_psr + has_panel_replay + has_sel_update documentation
in the begin of intel_psr.c.

BR,

Jouni Högander

> 
> Regards,
> Suraj Kandpal
> 
> > void intel_psr_post_plane_update(struct intel_atomic_state *state,
> >                                  struct intel_crtc *crtc)
> > {
> >         struct drm_i915_private *dev_priv = to_i915(state-
> > >base.dev);
> >         const struct intel_crtc_state *crtc_state =
> >                 intel_atomic_get_new_crtc_state(state, crtc);
> >         struct intel_encoder *encoder;
> > 
> >         if (!crtc_state->has_psr)
> >                 return;
> > 
> > path to intel_psr_activate is intel_psr_post_plane_update-
> > > intel_psr_enable_locked->intel_psr_activate.
> > 
> > BR,
> > 
> > Jouni Högander
> > 
> > > 
> > > Regards,
> > > Suraj Kandpal
> > > 
> > > > 
> > > > BR,
> > > > 
> > > > Jouni Högander
> > > > 
> > > > > Regards,
> > > > > Suraj Kandpal
> > > > > 
> > > > > > 
> > > > > > BR,
> > > > > > 
> > > > > > Jouni Högander
> > > > > > 
> > > > > > >         val |=
> > > > > > > EDP_PSR_IDLE_FRAMES(psr_compute_idle_frames(intel_dp));
> > > > > > > 
> > > > > > >         if (DISPLAY_VER(dev_priv) < 20) @@ -907,7 +982,10
> > > > > > > @@
> > > > > > > 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: 16023497226*/
> > > > > > > +       if (intel_dp->psr.is_dpkgc_configured &&
> > > > > > > +           intel_psr_is_dc5_entry_possible(dev_priv))
> > > > > > > +               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; @@ -1502,6
> > > > > > > +1580,8 @@
> > > > > > > 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);
> > > > > > > +       intel_dp->psr.delayed_vblank =
> > > > > > > intel_psr_check_delayed_vblank_limit(crtc_state);
> > > > > > > +       intel_dp->psr.is_dpkgc_configured =
> > > > > > > intel_psr_is_dpkgc_configured(dev_priv);
> > > > > > >  }
> > > > > > > 
> > > > > > >  void intel_psr_get_config(struct intel_encoder *encoder,
> > > > > 
> > > 
>