Re: [Intel-gfx] [PATCH v5 3/8] drm/i915/kbl: IPC workaround for kabylake

[Paulo Zanoni]

Em Sex, 2016-11-18 às 20:39 +0530, Mahesh Kumar escreveu:
> IPC (Isoch Priority Control) may cause underflows.
> 
> KBL WA: When IPC is enabled, watermark latency values must be
> increased
> by 4us across all levels. This brings level 0 up to 6us.
> 
> Signed-off-by: Mahesh Kumar 
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 4 
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c
> b/drivers/gpu/drm/i915/intel_pm.c
> index 7090a7c..df39b50 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3599,6 +3599,10 @@ static int skl_compute_plane_wm(const struct
> drm_i915_private *dev_priv,
>   return 0;
>   }
>  
> + /* IPC WA for kabylake */
> + if (IS_KABYLAKE(dev_priv) && dev_priv->ipc_enabled)
> + latency += 4;
> +

Nitpick: put this a little below so it's next to the other code that
changes the latency.

With or without this:
Reviewed-by: Paulo Zanoni 

>   y_tiled = fb->modifier == I915_FORMAT_MOD_Y_TILED ||
>   fb->modifier ==
> I915_FORMAT_MOD_Yf_TILED;
>   x_tiled = fb->modifier == I915_FORMAT_MOD_X_TILED;
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[Intel-gfx] [PATCH v5 3/8] drm/i915/kbl: IPC workaround for kabylake

[Mahesh Kumar]

IPC (Isoch Priority Control) may cause underflows.

KBL WA: When IPC is enabled, watermark latency values must be increased
by 4us across all levels. This brings level 0 up to 6us.

Signed-off-by: Mahesh Kumar 
---
 drivers/gpu/drm/i915/intel_pm.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7090a7c..df39b50 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3599,6 +3599,10 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
return 0;
}
 
+   /* IPC WA for kabylake */
+   if (IS_KABYLAKE(dev_priv) && dev_priv->ipc_enabled)
+   latency += 4;
+
y_tiled = fb->modifier == I915_FORMAT_MOD_Y_TILED ||
fb->modifier == I915_FORMAT_MOD_Yf_TILED;
x_tiled = fb->modifier == I915_FORMAT_MOD_X_TILED;
-- 
2.10.1

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