Re: [PATCH 2/2] drm/i915/watermark: Modify latency programmed into PKG_C_LATENCY

["Govindapillai, Vinod" <vinod.govindapillai@intel.com>]

On Thu, 2024-11-14 at 10:00 +0530, Suraj Kandpal wrote:
> 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
Is this a normal practice? I didnt find any other than one of your prev patch. I wonder if the bspec
number more useful here?

Otherwise, looks ok after addressing the comments in prev patch. 

BR
Vinod

> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_wm.c | 22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_wm.c b/drivers/gpu/drm/i915/display/intel_wm.c
> index 620873d1244f..ce11a69b36cc 100644
> --- a/drivers/gpu/drm/i915/display/intel_wm.c
> +++ b/drivers/gpu/drm/i915/display/intel_wm.c
> @@ -157,9 +157,10 @@ intel_program_dpkgc_latency(struct intel_atomic_state *state,
>         struct intel_display *display = to_intel_display(state);
>         struct intel_crtc *crtc;
>         struct intel_crtc_state *new_crtc_state;
> -       u32 max_latency = LNL_PKG_C_LATENCY_MASK;
> +       u32 latency = LNL_PKG_C_LATENCY_MASK;
>         u32 clear = 0, val = 0;
>         u32 added_waketime = 0;
> +       u32 max_linetime = 0;
>         int i;
>         bool fixed_refresh_rate = false;
>  
> @@ -171,18 +172,29 @@ intel_program_dpkgc_latency(struct intel_atomic_state *state,
>                      new_crtc_state->vrr.vmin == new_crtc_state->vrr.flipline) ||
>                     !new_crtc_state->vrr.enable)
>                         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;
> +               }
> +
>                 added_waketime = 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_waketime);
>  
>         intel_de_rmw(display, LNL_PKG_C_LATENCY, clear, val);