Re: [Intel-gfx] [PATCH v9 6/8] drm/i915: WA for platforms with double buffered address update enable bit

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Sep 16, 2020 at 08:38:22PM +0530, Karthik B S wrote:
> In Gen 9 and Gen 10 platforms, async address update enable bit is
> double buffered. Due to this, during the transition from async flip
> to sync flip we have to wait until this bit is updated before continuing
> with the normal commit for sync flip.
> 
> v9: -Rename skl_toggle_async_sync() to skl_disable_async_flip_wa(). (Ville)
>     -Place the declarations appropriately as per need. (Ville)
>     -Take the lock before the reg read. (Ville)
>     -Fix comment and formatting. (Ville)
>     -Use IS_GEN_RANGE() for gen check. (Ville)
>     -Move skl_disable_async_flip_wa() to intel_pre_plane_update(). (Ville)
> 
> Signed-off-by: Karthik B S <karthik.b.s@intel.com>
> Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 46 ++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 0f0bcbb00c7f..6f6edc581e14 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -6562,6 +6562,43 @@ static void intel_post_plane_update(struct intel_atomic_state *state,
>  		icl_wa_scalerclkgating(dev_priv, pipe, false);
>  }
>  
> +static void skl_disable_async_flip_wa(struct intel_atomic_state *state,
> +				      struct intel_crtc *crtc,
> +				      const struct intel_crtc_state *new_crtc_state)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
> +	struct intel_plane *plane;
> +	struct intel_plane_state *new_plane_state;
> +	int i;
> +
> +	for_each_new_intel_plane_in_state(state, plane, new_plane_state, i) {
> +		u32 update_mask = new_crtc_state->update_planes;
> +		u32 plane_ctl, surf_addr;
> +		enum plane_id plane_id;
> +		unsigned long irqflags;
> +		enum pipe pipe;
> +
> +		if (crtc->pipe != plane->pipe ||
> +		    !(update_mask & BIT(plane->id)))
> +			continue;
> +
> +		plane_id = plane->id;
> +		pipe = plane->pipe;
> +
> +		spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
> +		plane_ctl = intel_de_read_fw(dev_priv, PLANE_CTL(pipe, plane_id));
> +		surf_addr = intel_de_read_fw(dev_priv, PLANE_SURF(pipe, plane_id));
> +
> +		plane_ctl &= ~PLANE_CTL_ASYNC_FLIP;
> +
> +		intel_de_write_fw(dev_priv, PLANE_CTL(pipe, plane_id), plane_ctl);
> +		intel_de_write_fw(dev_priv, PLANE_SURF(pipe, plane_id), surf_addr);
> +		spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> +	}
> +
> +	intel_wait_for_vblank(dev_priv, crtc->pipe);
> +}
> +
>  static void intel_pre_plane_update(struct intel_atomic_state *state,
>  				   struct intel_crtc *crtc)
>  {
> @@ -6647,6 +6684,15 @@ static void intel_pre_plane_update(struct intel_atomic_state *state,
>  	 */
>  	if (IS_GEN(dev_priv, 2) && planes_disabling(old_crtc_state, new_crtc_state))
>  		intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, false);
> +
> +	/*
> +	 * WA for platforms where async address update enable bit
> +	 * is double buffered and only latched at start of vblank.
> +	 */
> +	if (old_crtc_state->uapi.async_flip &&
> +	    !new_crtc_state->uapi.async_flip &&
> +	    IS_GEN_RANGE(dev_priv, 9, 10))
> +		skl_disable_async_flip_wa(state, crtc, new_crtc_state);
>  }
>  
>  static void intel_crtc_disable_planes(struct intel_atomic_state *state,
> -- 
> 2.22.0

-- 
Ville Syrjälä
Intel
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