[Intel-gfx] [PATCH] drm/i915: Fix divide by zero on watermark update

[Damien Lespiau]

On Thu, Jul 16, 2015 at 07:36:51PM +0300, Mika Kuoppala wrote:
> Fix divide by zero if we end up updating the watermarks
> with zero dotclock.
> 
> This is a stop gap measure to allow module load in cases
> where our state keeping fails.
> 
> v2: WARN_ON added (Paulo)
> 
> Cc: Paulo Zanoni <przanoni at gmail.com>
> Cc: Damien Lespiau <damien.lespiau at intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>

I want to say a loading module is more important than a proper fix, so:

Reviewed-by: Damien Lespiau <damien.lespiau at intel.com>

-- 
Damien

> ---
>  drivers/gpu/drm/i915/intel_pm.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 5eeddc9..0d3e014 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3316,8 +3316,10 @@ skl_compute_linetime_wm(struct drm_crtc *crtc, struct skl_pipe_wm_parameters *p)
>  	if (!to_intel_crtc(crtc)->active)
>  		return 0;
>  
> -	return DIV_ROUND_UP(8 * p->pipe_htotal * 1000, p->pixel_rate);
> +	if (WARN_ON(p->pixel_rate == 0))
> +		return 0;
>  
> +	return DIV_ROUND_UP(8 * p->pipe_htotal * 1000, p->pixel_rate);
>  }
>  
>  static void skl_compute_transition_wm(struct drm_crtc *crtc,
> -- 
> 2.1.4
>