[Intel-gfx] [PATCH V3] drm/i915/gen11: Disable cursor clock gating in HDR mode

[Surendrakumar Upadhyay, TejaskumarX]

> -----Original Message-----
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Sent: 18 June 2021 18:15
> To: Surendrakumar Upadhyay, TejaskumarX
> <tejaskumarx.surendrakumar.upadhyay at intel.com>
> Cc: intel-gfx at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH V3] drm/i915/gen11: Disable cursor clock
> gating in HDR mode
> 
> On Fri, Jun 18, 2021 at 05:16:06PM +0530, Tejas Upadhyay wrote:
> > Display underrun in HDR mode when cursor is enabled.
> > RTL fix will be implemented CLKGATE_DIS_PSL_A bit 28-46520h.
> > As per W/A 1604331009, Disable cursor clock gating in HDR mode.
> >
> > Bspec : 33451
> >
> > Changes since V2:
> >         - Made it general gen11 WA
> >         - Removed WA needed check
> >         - Added cursor plane active check
> >         - Once WA enable, software will not disable Changes since V1:
> >         - Modified way CLKGATE_DIS_PSL bit 28 was modified
> >
> > Cc: Souza Jose <jose.souza at intel.com>
> > Signed-off-by: Tejas Upadhyay
> > <tejaskumarx.surendrakumar.upadhyay at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 15 +++++++++++++++
> >  drivers/gpu/drm/i915/i915_reg.h              |  5 +++++
> >  2 files changed, 20 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 6be1b31af07b..99b33455b945 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -383,6 +383,18 @@ icl_wa_scalerclkgating(struct drm_i915_private
> *dev_priv, enum pipe pipe,
> >  		               intel_de_read(dev_priv, CLKGATE_DIS_PSL(pipe)) &
> > ~DPFR_GATING_DIS);  }
> >
> > +/* Wa_1604331009:icl,jsl,ehl */
> > +static void
> > +icl_wa_cursorclkgating(struct drm_i915_private *dev_priv, enum pipe
> > +pipe,
> 
> Pointless function arguments since they can be derived from the crtc state.
> 
> > +		       const struct intel_crtc_state *crtc_state) {
> > +	if (crtc_state->active_planes & icl_hdr_plane_mask() &&
> 
> That doesn't mean HDR mode will be enabled. I would suggest extracting the
> HDR mode stuff from bdw_set_pipemisc() into a small helper. Or
> alternatively we could stick that into the crtc state even.

Sure. I will try that. Would you suggest best way to test this? I was testing using playing HDR video on HDR monitor with WA implemented.

Thanks,
Tejas
> 
> > +	    crtc_state->active_planes & BIT(PLANE_CURSOR) &&
> 
> > +	    IS_GEN(dev_priv, 11))
> > +		intel_de_rmw(dev_priv, CLKGATE_DIS_PSL(pipe),
> > +			     CURSOR_GATING_DIS, CURSOR_GATING_DIS); }
> 
> Where does it get turned back on?

As per Jose's review in last version, I have removed W/A disable change. Please see below :

" Like the idea of only enable the WA when a HDR plane is enabled but 
there is some problems:
- never disable the wa
- not checking if a cursor plane is also active
- calling it in the post and pre plane update, I think only the pre is 
needed
- checking the old state, no need to do optimizations like that for 
just one MMIO write"

Thanks,
Tejas
> 
> > +
> >  static bool
> >  is_trans_port_sync_slave(const struct intel_crtc_state *crtc_state)
> > { @@ -2939,6 +2951,9 @@ static void intel_pre_plane_update(struct
> > intel_atomic_state *state,
> >  	    needs_scalerclk_wa(new_crtc_state))
> >  		icl_wa_scalerclkgating(dev_priv, pipe, true);
> >
> > +	/* Wa_1604331009:icl,jsl,ehl */
> > +	icl_wa_cursorclkgating(dev_priv, pipe, new_crtc_state);
> > +
> >  	/*
> >  	 * Vblank time updates from the shadow to live plane control register
> >  	 * are blocked if the memory self-refresh mode is active at that
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> > b/drivers/gpu/drm/i915/i915_reg.h index 955027799d1d..bbdd8429297d
> > 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -4235,6 +4235,11 @@ enum {
> >  #define INF_UNIT_LEVEL_CLKGATE		_MMIO(0x9560)
> >  #define   CGPSF_CLKGATE_DIS		(1 << 3)
> >
> > +/*
> > + * GEN11 clock gating regs
> > + */
> > +#define   CURSOR_GATING_DIS            BIT(28)
> > +
> >  /*
> >   * Display engine regs
> >   */
> > --
> > 2.31.1
> >
> > _______________________________________________
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> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> --
> Ville Syrjälä
> Intel