On Thu, Mar 26, 2020 at 08:10:00PM +0200, Stanislav Lisovskiy wrote:
> Addressing one of the comments, recommending to extract platform
> specific code from intel_can_enable_sagv as a preparation, before
> we are going to add support for tgl+.
> 
> Current code in intel_can_enable_sagv is valid only for skl,
> so this patch adds also proper support for icl, subsequent
> patches will add support for tgl+, combined with other required
> changes.
> 
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 89 ++++++++++++++++++++++-----------
>  1 file changed, 61 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index f8d62d1977ac..64193b098175 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3757,41 +3757,24 @@ intel_disable_sagv(struct drm_i915_private *dev_priv)
>       return 0;
>  }
>  
> -bool intel_can_enable_sagv(struct intel_atomic_state *state)
> +static bool icl_can_enable_sagv_on_pipe(struct intel_crtc_state *crtc_state)

icl_crtc_can_enable_sagv()/etc. would be more consistent with existing
practices. crtc_state can be const.

>  {
> -     struct drm_device *dev = state->base.dev;
> +     struct drm_device *dev = crtc_state->uapi.crtc->dev;

IMO just remove this 'dev' variable.

>       struct drm_i915_private *dev_priv = to_i915(dev);
>       struct intel_crtc *crtc;
>       struct intel_plane *plane;
> -     struct intel_crtc_state *crtc_state;
> -     enum pipe pipe;
> +     struct intel_plane_state *plane_state;

const

>       int level, latency;
>  
> -     if (!intel_has_sagv(dev_priv))
> -             return false;
> +     crtc = to_intel_crtc(crtc_state->uapi.crtc);

Initialize when declaring.

>  
> -     /*
> -      * If there are no active CRTCs, no additional checks need be performed
> -      */
> -     if (hweight8(state->active_pipes) == 0)
> -             return true;
> -
> -     /*
> -      * SKL+ workaround: bspec recommends we disable SAGV when we have
> -      * more then one pipe enabled
> -      */
> -     if (hweight8(state->active_pipes) > 1)
> -             return false;
> -
> -     /* Since we're now guaranteed to only have one active CRTC... */
> -     pipe = ffs(state->active_pipes) - 1;
> -     crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
> -     crtc_state = to_intel_crtc_state(crtc->base.state);

We seem to be missing a hw.active check.

> -
> -     if (crtc_state->hw.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE)
> +     if (crtc_state->hw.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE) {
> +             DRM_DEBUG_KMS("No SAGV for interlaced mode on pipe %c\n",
> +                           pipe_name(crtc->pipe));
>               return false;
> +     }
>  
> -     for_each_intel_plane_on_crtc(dev, crtc, plane) {
> +     intel_atomic_crtc_state_for_each_plane_state(plane, plane_state, 
> crtc_state) {
>               struct skl_plane_wm *wm =
>                       &crtc_state->wm.skl.optimal.planes[plane->id];
>  
> @@ -3807,7 +3790,7 @@ bool intel_can_enable_sagv(struct intel_atomic_state 
> *state)
>               latency = dev_priv->wm.skl_latency[level];
>  
>               if (skl_needs_memory_bw_wa(dev_priv) &&
> -                 plane->base.state->fb->modifier ==
> +                 plane_state->uapi.fb->modifier ==
>                   I915_FORMAT_MOD_X_TILED)
>                       latency += 15;
>  
> @@ -3816,8 +3799,58 @@ bool intel_can_enable_sagv(struct intel_atomic_state 
> *state)
>                * incur memory latencies higher than sagv_block_time_us we
>                * can't enable SAGV.
>                */
> -             if (latency < dev_priv->sagv_block_time_us)
> +             if (latency < dev_priv->sagv_block_time_us) {
> +                     DRM_DEBUG_KMS("Latency %d < sagv block time %d, no SAGV 
> for pipe %c\n",
> +                                   latency, dev_priv->sagv_block_time_us, 
> pipe_name(crtc->pipe));
>                       return false;

How much noise will these debugs generate?

> +             }
> +     }
> +
> +     return true;
> +}
> +
> +static bool skl_can_enable_sagv_on_pipe(struct intel_crtc_state *crtc_state)
> +{
> +     struct intel_atomic_state *state = 
> to_intel_atomic_state(crtc_state->uapi.state);
> +
> +     /*
> +      * It has been recommended that for Gen 9 we switch SAGV off when
> +      * multiple pipes are used.
> +      */
> +     if (hweight8(state->active_pipes) > 1)
> +             return false;
> +
> +     /*
> +      * Besides active pipe limitation, rest of checks pretty much match ICL
> +      * so no need to duplicate code
> +      */
> +     return icl_can_enable_sagv_on_pipe(crtc_state);
> +}
> +
> +bool intel_can_enable_sagv(struct intel_atomic_state *state)
> +{
> +     struct drm_device *dev = state->base.dev;

Pls don't add needless 'dev' variables.

> +     struct drm_i915_private *dev_priv = to_i915(dev);
> +     struct intel_crtc *crtc;
> +     struct intel_crtc_state *crtc_state;

const

> +     int i;
> +
> +     if (!intel_has_sagv(dev_priv))
> +             return false;
> +
> +     /*
> +      * If there are no active CRTCs, no additional checks need be performed
> +      */
> +     if (hweight8(state->active_pipes) == 0)
> +             return true;

Seems pointless.

> +
> +     for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {

Hmm. I think this is now temporarily busted since we only consider
the crtcs in the state. Would seem like we need to introduce the
sagv bitmaks first/at the same time as we do this.

> +             if (INTEL_GEN(dev_priv) <= 9) {
> +                     if (!skl_can_enable_sagv_on_pipe(crtc_state))
> +                             return false;
> +             } else if (!icl_can_enable_sagv_on_pipe(crtc_state)) {
> +                     return false;
> +             }

Very hard to read if-else construct. Plase make it consistent for both
branches, and put the icl+ case first.

>       }
>  
>       return true;
> -- 
> 2.24.1.485.gad05a3d8e5

-- 
Ville Syrjälä
Intel
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