Re: [PATCH v2 3/4] drm/i915/alpm: Calculate ALPM Entry check

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

On Mon, 2024-01-29 at 02:08 +0000, Murthy, Arun R wrote:
> 
> 
> > -----Original Message-----
> > From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf
> > Of Jouni
> > Högander
> > Sent: Friday, January 5, 2024 7:45 PM
> > To: intel-gfx@lists.freedesktop.org
> > Subject: [PATCH v2 3/4] drm/i915/alpm: Calculate ALPM Entry check
> > 
> > ALPM Entry Check represents the number of lines needed to put the
> > main link
> > to sleep and keep it in the sleep state before it can be taken out
> > of the SLEEP
> > state (eDP requires the main link to be in the SLEEP state for a
> > minimum of
> > 5us).
> > 
> > Bspec: 71477
> > 
> > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > ---
> >  .../drm/i915/display/intel_display_types.h    |  3 ++
> >  drivers/gpu/drm/i915/display/intel_psr.c      | 28
> > +++++++++++++++++++
> >  2 files changed, 31 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> > b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index 889a8b34b7ac..7eddef859ff4 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1680,6 +1680,9 @@ struct intel_pps {  struct alpm_parameters {
> >         u8 io_wake_lines;
> >         u8 fast_wake_lines;
> > +
> > +       /* LNL and beyond */
> > +       u8 check_entry_lines;
> >  };
> > 
> >  struct intel_psr {
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 1709ebb31215..7fbd18f21c3b 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -1099,6 +1099,28 @@ static bool
> > _compute_psr2_sdp_prior_scanline_indication(struct intel_dp
> > *intel_d
> >         return true;
> >  }
> > 
> > +static bool _lnl_compute_alpm_params(struct intel_dp *intel_dp,
> > +                                    struct intel_crtc_state
> > *crtc_state) {
> > +       struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > +       struct alpm_parameters *alpm_params = &intel_dp-
> > >psr.alpm_params;
> > +       int check_entry_lines;
> > +
> > +       /* ALPM Entry Check = 2 + CEILING( 5us /tline ) */
> > +       check_entry_lines = 2 +
> > +               intel_usecs_to_scanlines(&crtc_state-
> > >hw.adjusted_mode, 5);
> > +
> > +       if (check_entry_lines > 15)
> > +               return false;
> > +
> > +       if (i915->display.params.psr_safest_params)
> > +               check_entry_lines = 15;
> > +
> > +       alpm_params->check_entry_lines = check_entry_lines;
> > +
> > +       return true;
> > +}
> > +
> >  static bool _compute_alpm_params(struct intel_dp *intel_dp,
> >                                  struct intel_crtc_state
> > *crtc_state)  { @@ -
> > 1114,6 +1136,8 @@ static bool _compute_alpm_params(struct intel_dp
> > *intel_dp,
> >                  * it is not enough -> use 45 us.
> >                  */
> >                 fast_wake_time = 45;
> > +
> > +               /* TODO: Check how we can use ALPM_CTL fast wake
> > extended
> > field */
> >                 max_wake_lines = 12;
> >         } else {
> >                 io_wake_time = 50;
> > @@ -1130,6 +1154,10 @@ static bool _compute_alpm_params(struct
> > intel_dp
> > *intel_dp,
> >             fast_wake_lines > max_wake_lines)
> >                 return false;
> > 
> > +       if (DISPLAY_VER(i915) >= 20 &&
> > !_lnl_compute_alpm_params(intel_dp,
> > +                                                               
> > crtc_state))
> The function name _lnl_*** indicates it should be display ver 20. So
> can this display ver check be moved to _lnl_*** ?

Yes, I can do that.

BR,

Jouni Högander

> 
> Thanks and Regards,
> Arun R Murthy
> -------------------
> > +               return false;
> > +
> >         if (i915->display.params.psr_safest_params)
> >                 io_wake_lines = fast_wake_lines = max_wake_lines;
> > 
> > --
> > 2.34.1
>