[PATCH v11 2/2] drm/i915/panelreplay: Panel replay workaround with VRR

[Manna, Animesh]

> -----Original Message-----
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Sent: Friday, September 20, 2024 5:10 PM
> To: Manna, Animesh <animesh.manna at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; Nikula, Jani <jani.nikula at intel.com>;
> Hogander, Jouni <jouni.hogander at intel.com>; Murthy, Arun R
> <arun.r.murthy at intel.com>; Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>;
> Golani, Mitulkumar Ajitkumar <mitulkumar.ajitkumar.golani at intel.com>
> Subject: Re: [PATCH v11 2/2] drm/i915/panelreplay: Panel replay
> workaround with VRR
> 
> On Mon, Sep 16, 2024 at 01:24:06PM +0530, Animesh Manna wrote:
> > Panel Replay VSC SDP not getting sent when VRR is enabled and W1 and
> > W2 are 0. So Program Set Context Latency in
> TRANS_SET_CONTEXT_LATENCY
> > register to at least a value of 1.
> > The same is applicable for PSR1/PSR2 as well.
> >
> > HSD: 14015406119
> >
> > v1: Initial version.
> > v2: Update timings stored in adjusted_mode struct. [Ville]
> > v3: Add WA in compute_config(). [Ville]
> > v4:
> > - Add DISPLAY_VER() check and improve code comment. [Rodrigo]
> > - Introduce centralized intel_crtc_vblank_delay(). [Ville]
> > v5: Move to crtc_compute_config(). [Ville]
> > v6: Restrict DISPLAY_VER till 14. [Mitul]
> > v7:
> > - Corrected code-comment. [Mitul]
> > - dev_priv local variable removed. [Jani]
> > v8: Introduce late_compute_config() which will take care late
> > vblank-delay adjustment. [Ville]
> > v9: Implementation simplified and split into multiple patches.
> > v10:
> > - Split vrr changes and use struct intel_display in DISPLAY_VER().
> > [Ankit]
> > - Use for_each_new_intel_connector_in_state(). [Jani]
> >
> > Signed-off-by: Animesh Manna <animesh.manna at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 33
> > +++++++++++++++++++-  drivers/gpu/drm/i915/display/intel_display.h |
> > 2 ++
> >  2 files changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 111e61eceafc..a0bd29b0d29a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -2529,7 +2529,18 @@ static int intel_crtc_compute_config(struct
> > intel_atomic_state *state,  {
> >  	struct intel_crtc_state *crtc_state =
> >  		intel_atomic_get_new_crtc_state(state, crtc);
> > -	int ret;
> > +	struct intel_connector *connector;
> > +	struct intel_digital_connector_state *conn_state;
> > +	int ret, i;
> > +
> > +	for_each_new_intel_connector_in_state(state, connector,
> conn_state, i) {
> > +		struct intel_encoder *encoder = connector->encoder;
> > +
> > +		if (conn_state->base.crtc != &crtc->base)
> > +			continue;
> > +
> > +		intel_crtc_adjust_vblank_delay(crtc_state, encoder);
> > +	}
> 
> Why is this loop here?

We can drop this loop, it was added when this piece of code is added in encoder compute-config.
 
> 
> >
> >  	ret = intel_dpll_crtc_compute_clock(state, crtc);
> >  	if (ret)
> > @@ -3940,6 +3951,26 @@ bool intel_crtc_get_pipe_config(struct
> intel_crtc_state *crtc_state)
> >  	return true;
> >  }
> >
> > +void intel_crtc_adjust_vblank_delay(struct intel_crtc_state *crtc_state,
> > +				    struct intel_encoder *encoder) {
> > +	struct intel_display *display = to_intel_display(encoder);
> > +	struct drm_display_mode *adjusted_mode =
> > +&crtc_state->hw.adjusted_mode;
> > +
> > +	/*
> > +	 * wa_14015401596 for display versions 13, 14.
> > +	 * Program Set Context Latency in TRANS_SET_CONTEXT_LATENCY
> register
> > +	 * to at least a value of 1 when PSR1/PSR2/Panel Replay is enabled
> with VRR.
> > +	 * Value for TRANS_SET_CONTEXT_LATENCY is calculated by
> substracting
> > +	 * crtc_vdisplay from crtc_vblank_start, so incrementing
> crtc_vblank_start
> > +	 * by 1 if both are equal.
> > +	 */
> > +	if (crtc_state->vrr.enable &&
> 
> Another case of the do not use.

Ok.

> 
> > crtc_state->has_psr &&
> 
> Does that cover panel replay as well?

Yes for panel replay also has_psr flag will be true.

> 
> Can this change dynamically during fastsets? If yes, then you can't use it for
> this, again due to fastset VRR requirements.
> 

has_psr flag will be set if both source and sink support panel-replay. It is applicable for psr/psr2 as well, but if vrr is enabled it will not be set. I do not see any dynamic condition will change the has_psr flag for panel-replay.
 
> 
> Did you actually test this code? AFAIK the fastset checks should catch this and
> refuse to toggle VRR with a fastset. If that's not the case then we have even
> bigger problems somewhere...

Have not tested the code due to unavailability of panel.
I will check fastest VRR path once more.

Regards,
Animesh

> 
> > +	    adjusted_mode->crtc_vblank_start == adjusted_mode-
> >crtc_vdisplay &&
> > +	    IS_DISPLAY_VER(display, 13, 14))
> > +		adjusted_mode->crtc_vblank_start += 1; }
> > +
> >  int intel_dotclock_calculate(int link_freq,
> >  			     const struct intel_link_m_n *m_n)  { diff --git
> > a/drivers/gpu/drm/i915/display/intel_display.h
> > b/drivers/gpu/drm/i915/display/intel_display.h
> > index 7ca26e5cb20e..db7bb5cac2f5 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display.h
> > @@ -429,6 +429,8 @@ bool intel_crtc_is_joiner_primary(const struct
> > intel_crtc_state *crtc_state);
> >  u8 intel_crtc_joiner_secondary_pipes(const struct intel_crtc_state
> > *crtc_state);  struct intel_crtc *intel_primary_crtc(const struct
> > intel_crtc_state *crtc_state);  bool intel_crtc_get_pipe_config(struct
> > intel_crtc_state *crtc_state);
> > +void intel_crtc_adjust_vblank_delay(struct intel_crtc_state *crtc_state,
> > +				    struct intel_encoder *encoder);
> >  bool intel_pipe_config_compare(const struct intel_crtc_state
> *current_config,
> >  			       const struct intel_crtc_state *pipe_config,
> >  			       bool fastset);
> > --
> > 2.29.0
> 
> --
> Ville Syrjälä
> Intel