Re: [PATCH v3 4/6] drm/i915/alpm: Add compute config for lobf

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

On Fri, 2024-05-03 at 08:42 +0000, Manna, Animesh wrote:
> 
> 
> > -----Original Message-----
> > From: Hogander, Jouni <jouni.hogander@intel.com>
> > Sent: Friday, May 3, 2024 12:49 PM
> > To: Manna, Animesh <animesh.manna@intel.com>; intel-
> > gfx@lists.freedesktop.org
> > Cc: dri-devel@lists.freedesktop.org; Murthy, Arun R
> > <arun.r.murthy@intel.com>; Nikula, Jani <jani.nikula@intel.com>
> > Subject: Re: [PATCH v3 4/6] drm/i915/alpm: Add compute config for
> > lobf
> > 
> > On Thu, 2024-04-25 at 00:08 +0530, Animesh Manna wrote:
> > > Link Off Between Active Frames, is a new feature for eDP
> > > that allows the panel to go to lower power state after
> > > transmission of data. This is a feature on top of ALPM, AS SDP.
> > > Add compute config during atomic-check phase.
> > > 
> > > v1: RFC version.
> > > v2: Add separate flag for auxless-alpm. [Jani]
> > > v3:
> > > - intel_dp->lobf_supported replaced with crtc_state->has_lobf.
> > > [Jouni]
> > > - Add DISPLAY_VER() check. [Jouni]
> > > - Modify function name of get_aux_less_status. [Jani]
> > > 
> > > Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_alpm.c     | 48
> > > +++++++++++++++++++
> > >  drivers/gpu/drm/i915/display/intel_alpm.h     |  5 ++
> > >  .../drm/i915/display/intel_display_types.h    |  4 ++
> > >  drivers/gpu/drm/i915/display/intel_dp.c       |  4 ++
> > >  4 files changed, 61 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> > > b/drivers/gpu/drm/i915/display/intel_alpm.c
> > > index 13bac3e8c8fa..3bb69ed16aab 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> > > @@ -11,6 +11,16 @@
> > >  #include "intel_dp_aux.h"
> > >  #include "intel_psr_regs.h"
> > > 
> > > +bool intel_alpm_get_aux_less_status(struct intel_dp *intel_dp)
> > > +{
> > > +       u8 alpm_caps = 0;
> > > +
> > > +       if (drm_dp_dpcd_readb(&intel_dp->aux,
> > > DP_RECEIVER_ALPM_CAP,
> > > +                             &alpm_caps) != 1)
> > > +               return false;
> > > +       return alpm_caps & DP_ALPM_AUX_LESS_CAP;
> > > +}
> > > +
> > >  /*
> > >   * See Bspec: 71632 for the table
> > >   *
> > > @@ -242,6 +252,44 @@ bool intel_alpm_compute_params(struct
> > > intel_dp
> > > *intel_dp,
> > >         return true;
> > >  }
> > > 
> > > +void intel_alpm_compute_lobf_config(struct intel_dp *intel_dp,
> > > +                                   struct intel_crtc_state
> > > *crtc_state,
> > > +                                   struct drm_connector_state
> > > *conn_state)
> > > +{
> > > +       struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > > +       struct drm_display_mode *adjusted_mode = &crtc_state-
> > > > hw.adjusted_mode;
> > > +       int waketime_in_lines, first_sdp_position;
> > > +       int context_latency, guardband;
> > > +
> > > +       crtc_state->has_lobf = false;
> > 
> > Drop this line. I think crtc_state is reset before doing this
> > compute_config
> 
> Sure.
> 
> > 
> > > +
> > > +       if (!intel_dp_is_edp(intel_dp))
> > > +               return;
> > > +
> > > +       if (DISPLAY_VER(i915) < 20)
> > > +               return;
> > > +
> > > +       if (!intel_dp_as_sdp_supported(intel_dp))
> > > +               return;
> > > +
> > > +       if (crtc_state->has_psr)
> > > +               return;
> > > +
> > > +       if (intel_alpm_compute_params(intel_dp, crtc_state)) {
> > 
> > I think it is easier to read and helps avoiding big if blocks if
> > you:
> > 
> > if (!intel_alpm_compute_params(intel_dp, crtc_state())
> >     return;
> 
> Ok.
> 
> > 
> > This actually brings up another thing: do we want to spread
> > intel_psr.c
> > pollution by continue using these boolean return values? I would
> > prefer
> > changing intel_alpm_compute_params return value to "normal" int
> > approach and return 0 on success. This would mean one more patch
> > changing it.
> 
> Ok.
> 
> > 
> > > +               context_latency = adjusted_mode-
> > > >crtc_vblank_start -
> > > adjusted_mode->crtc_vdisplay;
> > > +               guardband = adjusted_mode->crtc_vtotal -
> > > +                           adjusted_mode->crtc_vdisplay -
> > > context_latency;
> > > +               first_sdp_position = adjusted_mode->crtc_vtotal -
> > > adjusted_mode->crtc_vsync_start;
> > > +               if (intel_dp-
> > > >alpm_parameters.auxless_alpm_supported)
> > > +                       waketime_in_lines = intel_dp-
> > > > alpm_parameters.io_wake_lines;
> > > +               else
> > > +                       waketime_in_lines = intel_dp-
> > > > alpm_parameters.fast_wake_lines;
> > > +
> > > +               if ((context_latency + guardband) >
> > > (first_sdp_position + waketime_in_lines))
> > > +                       crtc_state->has_lobf = true;
> > 
> > crtc_state->has_lobf = (context_latency + guardband) >
> > (first_sdp_position + waketime_in_lines);
> 
> Ok.
> 
> > 
> > > +       }
> > > +}
> > > +
> > >  static void lnl_alpm_configure(struct intel_dp *intel_dp)
> > >  {
> > >         struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > > diff --git a/drivers/gpu/drm/i915/display/intel_alpm.h
> > > b/drivers/gpu/drm/i915/display/intel_alpm.h
> > > index c45d078e5a6b..b9602b71d28f 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_alpm.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_alpm.h
> > > @@ -10,9 +10,14 @@
> > > 
> > >  struct intel_dp;
> > >  struct intel_crtc_state;
> > > +struct drm_connector_state;
> > > 
> > > +bool intel_alpm_get_aux_less_status(struct intel_dp *intel_dp);
> > >  bool intel_alpm_compute_params(struct intel_dp *intel_dp,
> > >                                struct intel_crtc_state
> > > *crtc_state);
> > > +void intel_alpm_compute_lobf_config(struct intel_dp *intel_dp,
> > > +                                   struct intel_crtc_state
> > > *crtc_state,
> > > +                                   struct drm_connector_state
> > > *conn_state);
> > >  void intel_alpm_configure(struct intel_dp *intel_dp);
> > > 
> > >  #endif
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > index d94f50c6dc6c..5a0ffd5aa48b 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > @@ -1405,6 +1405,9 @@ struct intel_crtc_state {
> > > 
> > >         /* for loading single buffered registers during vblank */
> > >         struct drm_vblank_work vblank_work;
> > > +
> > > +       /* LOBF flag */
> > > +       bool has_lobf;
> > >  };
> > > 
> > >  enum intel_pipe_crc_source {
> > > @@ -1835,6 +1838,7 @@ struct intel_dp {
> > >                 u8 fast_wake_lines;
> > > 
> > >                 /* LNL and beyond */
> > > +               bool auxless_alpm_supported;
> > >                 u8 check_entry_lines;
> > >                 u8 silence_period_sym_clocks;
> > >                 u8 lfps_half_cycle_num_of_syms;
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > > b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index e05e25cd4a94..563739c6014c 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -48,6 +48,7 @@
> > >  #include "i915_drv.h"
> > >  #include "i915_irq.h"
> > >  #include "i915_reg.h"
> > > +#include "intel_alpm.h"
> > >  #include "intel_atomic.h"
> > >  #include "intel_audio.h"
> > >  #include "intel_backlight.h"
> > > @@ -2997,6 +2998,7 @@ intel_dp_compute_config(struct
> > > intel_encoder
> > > *encoder,
> > >         intel_vrr_compute_config(pipe_config, conn_state);
> > >         intel_dp_compute_as_sdp(intel_dp, pipe_config);
> > >         intel_psr_compute_config(intel_dp, pipe_config,
> > > conn_state);
> > > +       intel_alpm_compute_lobf_config(intel_dp, pipe_config,
> > > conn_state);
> > >         intel_dp_drrs_compute_config(connector, pipe_config,
> > > link_bpp_x16);
> > >         intel_dp_compute_vsc_sdp(intel_dp, pipe_config,
> > > conn_state);
> > >         intel_dp_compute_hdr_metadata_infoframe_sdp(intel_dp,
> > > pipe_config, conn_state);
> > > @@ -6612,6 +6614,8 @@ static bool intel_edp_init_connector(struct
> > > intel_dp *intel_dp,
> > > 
> > >         intel_pps_init_late(intel_dp);
> > > 
> > > +       intel_dp->alpm_parameters.auxless_alpm_supported =
> > > intel_alpm_get_aux_less_status(intel_dp);
> > 
> > How about aux_wake ?
> 
> I felt auxless_alpm_supported will give both aux-less and aux-wake
> info, if it is true then aux-less otherwise aux-wake. Do you see any
> issue here?

If panel supports only AUX Wake?

BR,

Jouni Högander

> 
> Regards,
> Animesh 
> > 
> > > +
> > >         return true;
> > > 
> > >  out_vdd_off:
>