[Intel-gfx] [PATCH V2] drm/i915/jsl: Disable cursor clock gating in HDR mode

[Surendrakumar Upadhyay, TejaskumarX]

> -----Original Message-----
> From: Souza, Jose <jose.souza at intel.com>
> Sent: 03 November 2020 05:32
> To: Surendrakumar Upadhyay, TejaskumarX
> <tejaskumarx.surendrakumar.upadhyay at intel.com>; intel-
> gfx at lists.freedesktop.org
> Cc: Pandey, Hariom <hariom.pandey at intel.com>
> Subject: Re: [PATCH V2] drm/i915/jsl: Disable cursor clock gating in HDR
> mode
> 
> On Mon, 2020-11-02 at 13:09 +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 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 | 28 ++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_reg.h              |  5 ++++
> >  2 files changed, 33 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index cddbda5303ff..b132585d9e78 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -541,6 +541,15 @@ icl_wa_scalerclkgating(struct drm_i915_private
> *dev_priv, enum pipe pipe,
> >                 intel_de_read(dev_priv, CLKGATE_DIS_PSL(pipe)) &
> > ~DPFR_GATING_DIS);  }
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> > +/* Wa_1604331009:jsl */
> > +static void
> > +jsl_wa_cursorclkgating(struct drm_i915_private *dev_priv, enum pipe
> pipe,
> > +       bool enable)
> 
> if this is a gen11 WA why naming as jsl? also include in the comment icl and
> ehl.
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> > +{
> > +intel_de_rmw(dev_priv, CLKGATE_DIS_PSL(pipe),
> > +     CURSOR_GATING_DIS, enable ? CURSOR_GATING_DIS : 0); }
> > +
> >  static bool
> >  needs_modeset(const struct intel_crtc_state *state)  { @@ -6637,6
> > +6646,16 @@ static bool needs_scalerclk_wa(const struct
> > intel_crtc_state *crtc_state)  return false;  }
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> > +static bool needs_cursorclk_wa(const struct intel_crtc_state
> > +*crtc_state) { struct drm_i915_private *dev_priv =
> > +to_i915(crtc_state->uapi.crtc->dev);
> 
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> > +/* Wa_1604331009:jsl */
> > +if (crtc_state->active_planes & icl_hdr_plane_mask() &&
> > +    IS_GEN(dev_priv, 11))
> > +return true;
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> > +return false;
> > +}
> > +
> >  static bool planes_enabling(const struct intel_crtc_state *old_crtc_state,
> >      const struct intel_crtc_state *new_crtc_state)  { @@ -6678,6
> > +6697,10 @@ static void intel_post_plane_update(struct
> > intel_atomic_state *state,  if (needs_scalerclk_wa(old_crtc_state) &&
> >      !needs_scalerclk_wa(new_crtc_state))
> >  icl_wa_scalerclkgating(dev_priv, pipe, false);
> > +
> > +if (needs_cursorclk_wa(old_crtc_state) &&
> > +    !needs_cursorclk_wa(new_crtc_state))
> > +jsl_wa_cursorclkgating(dev_priv, pipe, false);
> >  }
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> >  static void skl_disable_async_flip_wa(struct intel_atomic_state
> > *state, @@ -6743,6 +6766,11 @@ static void
> intel_pre_plane_update(struct intel_atomic_state *state,
> >      needs_scalerclk_wa(new_crtc_state))
> >  icl_wa_scalerclkgating(dev_priv, pipe, true);
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> > +/* Wa_1604331009:jsl */
> > +if (!needs_cursorclk_wa(old_crtc_state) &&
> > +    needs_cursorclk_wa(new_crtc_state))
> > +jsl_wa_cursorclkgating(dev_priv, pipe, true);
> 
> 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
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> other thing, would be better have the wa function being called and inside of
> that function it will check if the WA is needed and write to the register, no
> need of a function to check if needs and another to apply the WA.

Tejas : I have addressed all above review comments in next patchset.

> 
> ICL WA description says that it can only be applied if "CUR_CTL[18],
> CUR_CTL[16] or CUR_COLOR_CTL[15]" is not set, did you checked if when a
> HDR plane is enabled it causes a complete modeset(disable pipe, set wa,
> enable pipe) in the pipe? if that happens it is complying if not we have a
> problem here.

Tejas : Would you elaborate more this scenario? As far as I understand once planes are attached to CRTC/pipe they can be updated runtime. Are you referring planes attached to CRTC/pipe will change while CRTC is enable? I would like to understand if I am missing something.  

> 
> > +
> >  /*
> >   * 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 bb0656875697..f81a503c5d4b
> > 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -4194,6 +4194,11 @@ enum {
> >  #define INF_UNIT_LEVEL_CLKGATE_MMIO(0x9560)
> >  #define   CGPSF_CLKGATE_DIS(1 << 3)
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> > +/*
> > + * GEN11 clock gating regs
> > + */
> > +#define   CURSOR_GATING_DISBIT(28)
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> should be defined between other CLKGATE_DIS_PSL bits.
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> > +
> >  /*
> >   * Display engine regs
> >   */
>