Re: [Intel-gfx] [PATCH V4] drm/i915/gen11: Disable cursor clock gating in HDR mode

["Surendrakumar Upadhyay, TejaskumarX" <tejaskumarx.surendrakumar.upadhyay@intel.com>]

> -----Original Message-----
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Sent: 02 September 2021 18:29
> To: Surendrakumar Upadhyay, TejaskumarX
> <tejaskumarx.surendrakumar.upadhyay@intel.com>
> Cc: intel-gfx@lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH V4] drm/i915/gen11: Disable cursor clock
> gating in HDR mode
> 
> On Thu, Sep 02, 2021 at 11:07:06AM +0000, Surendrakumar Upadhyay,
> TejaskumarX wrote:
> >
> >
> > > -----Original Message-----
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Sent: 01 September 2021 19:19
> > > To: Surendrakumar Upadhyay, TejaskumarX
> > > <tejaskumarx.surendrakumar.upadhyay@intel.com>
> > > Cc: intel-gfx@lists.freedesktop.org
> > > Subject: Re: [Intel-gfx] [PATCH V4] drm/i915/gen11: Disable cursor
> > > clock gating in HDR mode
> > >
> > > On Tue, Jun 22, 2021 at 03:04:24PM +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 V3:
> > > > 	- Disable WA when not in HDR mode or cursor plane not active - Ville
> > > > 	- Extract required args from crtc_state - Ville
> > > > 	- Create HDR mode API using bdw_set_pipemisc ref - Ville
> > > > 	- Tested with HDR video as well full setmode, WA applies and
> > > disables
> > > > 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@intel.com>
> > > > Signed-off-by: Tejas Upadhyay
> > > > <tejaskumarx.surendrakumar.upadhyay@intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/display/intel_display.c | 27
> ++++++++++++++++++++
> > > >  drivers/gpu/drm/i915/i915_reg.h              |  5 ++++
> > > >  2 files changed, 32 insertions(+)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > > > b/drivers/gpu/drm/i915/display/intel_display.c
> > > > index 6be1b31af07b..e1ea03b918df 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > > > @@ -358,6 +358,13 @@ static void intel_update_czclk(struct
> > > drm_i915_private *dev_priv)
> > > >  		dev_priv->czclk_freq);
> > > >  }
> > > >
> > > > +static bool
> > > > +is_hdr_mode(const struct intel_crtc_state *crtc_state) {
> > > > +	return (crtc_state->active_planes & ~(icl_hdr_plane_mask() |
> > > > +		BIT(PLANE_CURSOR))) == 0;
> > > > +}
> > >
> > > Please use this in bdw_set_pipemisc() as well. This could be a
> > > separate prep patch actually.
> > >
> > > > +
> > > >  /* WA Display #0827: Gen9:all */
> > > >  static void
> > > >  skl_wa_827(struct drm_i915_private *dev_priv, enum pipe pipe,
> > > > bool
> > > > enable) @@ -383,6 +390,23 @@ 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(const struct intel_crtc_state *crtc_state) {
> > > > +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > > > +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> > > > +
> > > > +	if (is_hdr_mode(crtc_state) &&
> > > > +	    crtc_state->active_planes & BIT(PLANE_CURSOR) &&
> > > > +	    IS_GEN(dev_priv, 11))
> > > > +		intel_de_rmw(dev_priv, CLKGATE_DIS_PSL(crtc->pipe),
> > > > +			     CURSOR_GATING_DIS, CURSOR_GATING_DIS);
> > > > +	else
> > > > +		intel_de_rmw(dev_priv, CLKGATE_DIS_PSL(crtc->pipe),
> > > > +			     CURSOR_GATING_DIS, 0);
> > > > +}
> > > > +
> > > >  static bool
> > > >  is_trans_port_sync_slave(const struct intel_crtc_state
> > > > *crtc_state) { @@ -2939,6 +2963,9 @@ 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(new_crtc_state);
> > >
> > > This looks a bit wrong. We shouldn't turn the clock gating back on
> > > until after HDR mode has been disabled.
> > >
> > > So please model this after skl_wa_827() and icl_wa_scalerclkgating()
> > > so that
> > > a) the ordering is correct, and b) the code between all three w/as
> > > looks consistent.
> >
> > I did not get what you are suggesting here. Can you please put psudo?
> > Currently as far as I see icl_wa_cursorclkgating is already modelled  after
> skl_wa_827() and icl_wa_scalerclkgating(). Are referring same Or something
> else?
> 
> It should look something like:
> 
> intel_pre_plane_update()
> {
> 	if (!needs_cursorclk_wa(old_crtc_state) &&
> 	    needs_cursorclk_wa(new_crtc_state))
> 		icl_wa_cursorclkgating(..., true);
> }
> 
> intel_post_plane_update()
> {
> 	if (needs_cursorclk_wa(old_crtc_state) &&
> 	    !needs_cursorclk_wa(new_crtc_state))
> 		icl_wa_cursorclkgating(..., false);
> }
> 

Tejas : In the previous version it was done this way only. But after review comments from Jose I had to change it. See "Changes since V2" section. Also you can check in previous versions of patch.

> 
> --
> Ville Syrjälä
> Intel