Re: [Intel-gfx] [PATCH v3 01/11] drm/i915: Update watermark state correctly in sanitize_watermarks

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org, stable@vger.kernel.org
Subject: Re: [Intel-gfx] [PATCH v3 01/11] drm/i915: Update watermark state correctly in sanitize_watermarks
Date: Fri, 10 Nov 2017 17:28:28 +0200	[thread overview]
Message-ID: <20171110152828.GE10981@intel.com> (raw)
In-Reply-To: <20171110113503.16253-1-maarten.lankhorst@linux.intel.com>

On Fri, Nov 10, 2017 at 12:34:53PM +0100, Maarten Lankhorst wrote:
> We no longer use intel_crtc->wm.active for watermarks any more,
> which was incorrect. But this uncovered a bug in sanitize_watermarks(),
> which meant that we wrote the correct watermarks, but the next
> update would still use the wrong hw watermarks for calculating.
> This caused all further updates to fail with -EINVAL and the
> log would reveal an error like the one below:
> 
> [   10.043902] [drm:ilk_validate_wm_level.part.8 [i915]] Sprite WM0 too large 56 (max 0)
> [   10.043960] [drm:ilk_validate_pipe_wm [i915]] LP0 watermark invalid
> [   10.044030] [drm:intel_crtc_atomic_check [i915]] No valid intermediate pipe watermarks are possible
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Fixes: b6b178a77210 ("drm/i915: Calculate ironlake intermediate watermarks correctly, v2.")
> Cc: stable@vger.kernel.org #v4.8+
> ---
>  drivers/gpu/drm/i915/intel_display.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 84817ccc5305..17665ee06c9a 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -14442,6 +14442,8 @@ static void sanitize_watermarks(struct drm_device *dev)
>  
>  		cs->wm.need_postvbl_update = true;
>  		dev_priv->display.optimize_watermarks(intel_state, cs);
> +
> +		to_intel_crtc_state(crtc->state)->wm = cs->wm;

Hmm. Oh we don't swap the state here. Looks like we shouldn't be using
anything else from the crtc state, so this should work AFAICS.

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

>  	}
>  
>  put_state:
> -- 
> 2.15.0
> 
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-- 
Ville Syrjälä
Intel OTC