[Intel-gfx] [PATCH 14/14] drm/i915: Add two-stage ILK-style watermark programming (v4)

[Maarten Lankhorst]

Hey,

It's worh nothing this series may have a soft dependency on Ville's cleanups,
because else pixel_rate == 0 during boot. :(

This patch breaks when the initial sprite watermarks are set on ironlake, but no sprite is enabled.

A naive fix is below, without it my laptop won't power the screen because intermediate wm calculation fails. :(

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 41a4dbaf600b..bf874ff97024 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2457,7 +2457,7 @@ static int ilk_compute_intermediate_wm(struct drm_device *dev,
 
 		a_wm->enable &= b_wm->enable;
 		a_wm->pri_val = max(a_wm->pri_val, b_wm->pri_val);
-		a_wm->spr_val = max(a_wm->spr_val, b_wm->spr_val);
+		a_wm->spr_val = a->sprites_enabled ? max(a_wm->spr_val, b_wm->spr_val) : 0;
 		a_wm->cur_val = max(a_wm->cur_val, b_wm->cur_val);
 		a_wm->fbc_val = max(a_wm->fbc_val, b_wm->fbc_val);
 	}


Op 15-09-15 om 04:19 schreef Matt Roper:
> <snip>
> @@ -13202,6 +13229,20 @@ static int intel_atomic_commit(struct drm_device *dev,
>  	/* FIXME: add subpixel order */
>  
>  	drm_atomic_helper_wait_for_vblanks(dev, state);
> +
> +	/*
> +	 * Now that the vblank has passed, we can go ahead and program the
> +	 * optimal watermarks on platforms that need two-step watermark
> +	 * programming.
> +	 *
> +	 * TODO: Move this (and other cleanup) to an async worker eventually.
> +	 */
> +	for_each_crtc_in_state(state, crtc, crtc_state, i) {
> +		intel_cstate = to_intel_crtc_state(crtc->state);
> +
> +		dev_priv->display.optimize_watermarks(intel_cstate);
> +	}
^Breaks on my skylake with a null pointer deref; I think you might want to hide it behind a if. :-)