RE: [PATCH v1] drm/i915/display: Add command line param for DC balance

Mon, 14 Sep 2026 22:42:50 -0700 


> -----Original Message-----
> From: Jani Nikula <[email protected]>
> Sent: 04 September 2026 14:14
> To: Golani, Mitulkumar Ajitkumar <[email protected]>;
> Borah, Chaitanya Kumar <[email protected]>; intel-
> [email protected]
> Cc: [email protected]; Nautiyal, Ankit K
> <[email protected]>
> Subject: RE: [PATCH v1] drm/i915/display: Add command line param for DC
> balance
> 
> On Fri, 04 Sep 2026, "Golani, Mitulkumar Ajitkumar"
> <[email protected]> wrote:
> >> -----Original Message-----
> >> From: Borah, Chaitanya Kumar <[email protected]>
> >> Sent: 28 August 2026 15:46
> >> To: Golani, Mitulkumar Ajitkumar
> >> <[email protected]>;
> >> [email protected]
> >> Cc: [email protected]; Nautiyal, Ankit K
> >> <[email protected]>
> >> Subject: Re: [PATCH v1] drm/i915/display: Add command line param for
> >> DC balance
> >>
> >>
> >>
> >> On 8/28/2026 2:20 PM, Mitul Golani wrote:
> >> > Add a new module parameter 'enable_dc_balance' to allow enabling or
> >> > disabling the VRR DC balance feature at runtime. The DC balance
> >> > computation in intel_vrr_dc_balance_compute_config() now honours
> >> > this parameter, so the feature can be toggled without recompiling.
> >> >
> >> > Signed-off-by: Mitul Golani <[email protected]>
> >> > ---
> >> >   drivers/gpu/drm/i915/display/intel_display_params.c | 3 +++
> >> >   drivers/gpu/drm/i915/display/intel_display_params.h | 1 +
> >> >   drivers/gpu/drm/i915/display/intel_vrr.c            | 4 +++-
> >> >   3 files changed, 7 insertions(+), 1 deletion(-)
> >> >
> >> > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c
> >> > b/drivers/gpu/drm/i915/display/intel_display_params.c
> >> > index 2aed110c5b09..ed3aa84c5d43 100644
> >> > --- a/drivers/gpu/drm/i915/display/intel_display_params.c
> >> > +++ b/drivers/gpu/drm/i915/display/intel_display_params.c
> >> > @@ -120,6 +120,9 @@ intel_display_param_named_unsafe(enable_psr,
> >> > int,
> >> 0400,
> >> >          "(0=disabled, 1=enable up to PSR1, 2=enable up to PSR2) "
> >> >          "Default: -1 (use per-chip default)");
> >> >
> >> > +intel_display_param_named_unsafe(enable_dc_balance, int, 0400,
> >> > +        "Enable DC Balance (0=disabled, 1=enable). Default: 1 (use
> >> > +per-chip default)");
> >> > +
> >> >   intel_display_param_named_unsafe(enable_panel_replay, int, 0400,
> >> >          "Enable Panel Replay (0=disabled, 1=enabled). Default: -1 (use
> >> > per-chip default)");
> >> >
> >> > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h
> >> > b/drivers/gpu/drm/i915/display/intel_display_params.h
> >> > index b95ecf728daa..8c28c27e2c46 100644
> >> > --- a/drivers/gpu/drm/i915/display/intel_display_params.h
> >> > +++ b/drivers/gpu/drm/i915/display/intel_display_params.h
> >> > @@ -46,6 +46,7 @@ struct drm_printer;
> >> >          param(bool, enable_dp_mst, true, 0600) \
> >> >          param(int, enable_fbc, -1, 0600) \
> >> >          param(int, enable_psr, -1, 0600) \
> >> > +        param(int, enable_dc_balance, false, 0600) \
> >>
> >> You mean true?
> >
> > Yes should be true by default. I will update in next revision.
> 
> My comment on the rationale of the whole module parameter is more
> important, but if we end up with this, the parameter types and values need to
> match, i.e. int and integers, bool and true/false.
> 
> BR,
> Jani.

Thanks Jani for review

I have fixed with new revision v2, the parameter is now bool with a false 
default, so type and value match.

> 
> >
> > Thanks
> >
> >>
> >> >          param(int, enable_panel_replay, -1, 0600) \
> >> >          param(bool, psr_safest_params, false, 0400) \
> >> >          param(bool, enable_psr2_sel_fetch, true, 0400) \ diff --git
> >> > a/drivers/gpu/drm/i915/display/intel_vrr.c
> >> > b/drivers/gpu/drm/i915/display/intel_vrr.c
> >> > index e36db1174440..1698c54e258b 100644
> >> > --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> >> > +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> >> > @@ -439,10 +439,12 @@ static bool
> >> > intel_vrr_dc_balance_possible(const
> >> struct intel_crtc_state *crtc_st
> >> >   static void
> >> >   intel_vrr_dc_balance_compute_config(struct intel_crtc_state
> *crtc_state)
> >> >   {
> >> > +        struct intel_display *display = to_intel_display(crtc_state);
> >> >          int guardband_usec, adjustment_usec;
> >> >          struct drm_display_mode *adjusted_mode =
> >> > &crtc_state->hw.adjusted_mode;
> >> >
> >> > -        if (!intel_vrr_dc_balance_possible(crtc_state) || !crtc_state-
> >> >vrr.enable)
> >> > +        if (!intel_vrr_dc_balance_possible(crtc_state) ||
> >> > +            !crtc_state->vrr.enable ||
> >> > +!display->params.enable_dc_balance)
> >> >                  return;
> >> >
> >> >          crtc_state->vrr.dc_balance.vmax = crtc_state->vrr.vmax;
> >
> 
> --
> Jani Nikula, Intel






















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