[PATCH 6/6] drm/i915/wm: Modify latency programmed into PKG_C_LATENCY

[Kandpal, Suraj]

> -----Original Message-----
> From: Golani, Mitulkumar Ajitkumar
> <mitulkumar.ajitkumar.golani at intel.com>
> Sent: Tuesday, December 3, 2024 1:35 PM
> To: Kandpal, Suraj <suraj.kandpal at intel.com>; intel-xe at lists.freedesktop.org;
> intel-gfx at lists.freedesktop.org
> Cc: Govindapillai, Vinod <vinod.govindapillai at intel.com>; Nikula, Jani
> <jani.nikula at intel.com>
> Subject: RE: [PATCH 6/6] drm/i915/wm: Modify latency programmed into
> PKG_C_LATENCY
> 
> 
> 
> > -----Original Message-----
> > From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of
> > Suraj Kandpal
> > Sent: 15 November 2024 21:31
> > To: intel-xe at lists.freedesktop.org; intel-gfx at lists.freedesktop.org
> > Cc: Govindapillai, Vinod <vinod.govindapillai at intel.com>; Nikula, Jani
> > <jani.nikula at intel.com>; Kandpal, Suraj <suraj.kandpal at intel.com>
> > Subject: [PATCH 6/6] drm/i915/wm: Modify latency programmed into
> > PKG_C_LATENCY
> >
> > Increase the latency programmed into PKG_C_LATENCY latency to be a
> > multiple of line time which is written into WM_LINETIME.
> >
> > --v2
> > -Fix commit subject line [Sai Teja]
> > -Use individual DISPLAY_VER checks instead of range [Sai Teja]
> > -Initialize max_linetime [Sai Teja]
> >
> > --v3
> > -take into account the scenario when adjusted_latency is 0 [Vinod]
> >
> > --v4
> > -rename adjusted_latency to latency [Mitul] -fix the condition in
> > which dpkgc is disabled [Vinod]
> >
> > --v5
> > -Add check to see if max_linetime is 0 [Vinod]
> >
> > WA: 22020299601
> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/skl_watermark.c | 20
> > +++++++++++++++-----
> >  1 file changed, 15 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c
> > b/drivers/gpu/drm/i915/display/skl_watermark.c
> > index 0cc843314358..e9a60d54afef 100644
> > --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> > +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> > @@ -2861,7 +2861,7 @@ intel_program_dpkgc_latency(struct
> > intel_atomic_state *state)
> >  	struct drm_i915_private *i915 = to_i915(display->drm);
> >  	struct intel_crtc *crtc;
> >  	struct intel_crtc_state *new_crtc_state;
> > -	u32 max_latency = LNL_PKG_C_LATENCY_MASK, added_wake_time =
> > 0;
> > +	u32 latency = LNL_PKG_C_LATENCY_MASK, added_wake_time = 0,
> > +max_linetime = 0;
> >  	u32 clear, val;
> >  	bool fixed_refresh_rate = false;
> >  	int i;
> > @@ -2874,18 +2874,28 @@ intel_program_dpkgc_latency(struct
> > intel_atomic_state *state)
> >  		    (new_crtc_state->vrr.vmin == new_crtc_state->vrr.vmax &&
> >  		     new_crtc_state->vrr.vmin == new_crtc_state->vrr.flipline))
> >  			fixed_refresh_rate = true;
> > +
> > +		max_linetime = max(new_crtc_state->linetime,
> > max_linetime);
> >  	}
> >
> >  	if (fixed_refresh_rate) {
> > -		max_latency = skl_watermark_max_latency(i915, 1);
> > -		if (max_latency == 0)
> > -			max_latency = LNL_PKG_C_LATENCY_MASK;
> > +		latency = skl_watermark_max_latency(i915, 1);
> > +		/* Wa_22020299601 */
> > +		if (latency) {
> > +			if ((DISPLAY_VER(display) == 20 ||
> > DISPLAY_VER(display) == 30) &&
> > +			    max_linetime)
> > +				latency = max_linetime *
> > +					DIV_ROUND_UP(latency,
> > max_linetime);
> > +		} else {
> > +			latency = LNL_PKG_C_LATENCY_MASK;
> > +		}
> > +
> 
> Can this help, to avoid nested conditions ?

Sure looks fine to me I can add this change

Regard,
Suraj Kandpal

> 
> if (fixed_refresh_rate) {
> 		latency = skl_watermark_max_latency(i915, 1);
> 
> 		/* Wa_22020299601*/
> 		if (latency && max_linetime && (DISPLAY_VER(display) == 20
> || DISPLAY_VER(display) == 30)) {
> 			latency = max_linetime * DIV_ROUND_UP(latency,
> max_linetime);
> 		} else if (!latency) {
> 			latency = LNL_PKG_C_LATENCY_MASK;
> 		}
> 
> >  		added_wake_time = DSB_EXE_TIME +
> >  			display->sagv.block_time_us;
> >  	}
> >
> >  	clear = LNL_ADDED_WAKE_TIME_MASK |
> > LNL_PKG_C_LATENCY_MASK;
> > -	val = REG_FIELD_PREP(LNL_PKG_C_LATENCY_MASK, max_latency) |
> > +	val = REG_FIELD_PREP(LNL_PKG_C_LATENCY_MASK, latency) |
> >  		REG_FIELD_PREP(LNL_ADDED_WAKE_TIME_MASK,
> > added_wake_time);
> >
> >  	intel_de_rmw(display, LNL_PKG_C_LATENCY, clear, val);
> > --
> > 2.34.1