Re: [PATCH] drm/i915: Convert BUG_ON(!pll->active) and friends to a WARN

[Daniel Vetter <daniel@ffwll.ch>]

On Sun, May 13, 2012 at 08:16:12PM +0100, Chris Wilson wrote:
> Turn a fatal lockup into a merely blank display with lots of shouty
> messages.
> 
> v2: Whilst in the area, convert the other BUG_ON into less fatal errors.
> In particular, note that we may be called on a PCH platform not using
> PLLs, such as Haswell, and so we do not always want to BUG_ON(!pll)
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Ok, I guess you want me to drop v1 of this again. I'll wait for a bit of
feedback on these two then (and the tested-by from qa on the 2nd one).
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_display.c |   21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 12dba60..f9e1e1c 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -1473,14 +1473,18 @@ out_unlock:
>  static void intel_enable_pch_pll(struct intel_crtc *intel_crtc)
>  {
>  	struct drm_i915_private *dev_priv = intel_crtc->base.dev->dev_private;
> -	struct intel_pch_pll *pll = intel_crtc->pch_pll;
> +	struct intel_pch_pll *pll;
>  	int reg;
>  	u32 val;
>  
> -	/* PCH only available on ILK+ */
> +	/* PCH PLLs only available on ILK, SNB and IVB */
>  	BUG_ON(dev_priv->info->gen < 5);
> -	BUG_ON(pll == NULL);
> -	BUG_ON(pll->refcount == 0);
> +	pll = intel_crtc->pch_pll;
> +	if (pll == NULL)
> +		return;
> +
> +	if (WARN_ON(pll->refcount == 0))
> +		return;
>  
>  	DRM_DEBUG_KMS("enable PCH PLL %x (active %d, on? %d)for crtc %d\n",
>  		      pll->pll_reg, pll->active, pll->on,
> @@ -1518,13 +1522,18 @@ static void intel_disable_pch_pll(struct intel_crtc *intel_crtc)
>  	if (pll == NULL)
>  	       return;
>  
> -	BUG_ON(pll->refcount == 0);
> +	if (WARN_ON(pll->refcount == 0))
> +		return;
>  
>  	DRM_DEBUG_KMS("disable PCH PLL %x (active %d, on? %d) for crtc %d\n",
>  		      pll->pll_reg, pll->active, pll->on,
>  		      intel_crtc->base.base.id);
>  
> -	BUG_ON(pll->active == 0);
> +	if (WARN_ON(pll->active == 0)) {
> +		assert_pch_pll_disabled(dev_priv, intel_crtc);
> +		return;
> +	}
> +
>  	if (--pll->active) {
>  		assert_pch_pll_enabled(dev_priv, intel_crtc);
>  		return;
> -- 
> 1.7.10
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48