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

[Golani, Mitulkumar Ajitkumar]

> -----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 ?

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