Re: [PATCH] drm/i915: Fix erroneous conversion to u8

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Aug 08, 2014 at 09:32:20PM +0300, Ville Syrjälä wrote:
> On Fri, Aug 08, 2014 at 07:25:57PM +0100, Damien Lespiau wrote:
> > adj was defined as u8. The issue is last_adj can be negative and adj is
> > initialized with:
> > 
> >   adj = dev_priv->rps.last_adj;
> > 
> > and we were also happily doing things like:
> > 
> >   if (adj < 0)
> > 
> > (thank static analysers!)
> > 
> > v2: Make new_delay an int in case we overflow the u8 in the intermediate
> >     computations. new_delay will get clamped at the end anyway. (Ville)
> > 
> > Cc: Deepak S <deepak.s@linux.intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Queued for -next, thanks for the patch.
-Daniel

> 
> > ---
> >  drivers/gpu/drm/i915/i915_irq.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index 9fdf738..8e6729e 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -1327,10 +1327,10 @@ static u32 vlv_c0_residency(struct drm_i915_private *dev_priv,
> >   * @dev_priv: DRM device private
> >   *
> >   */
> > -static u32 vlv_calc_delay_from_C0_counters(struct drm_i915_private *dev_priv)
> > +static int vlv_calc_delay_from_C0_counters(struct drm_i915_private *dev_priv)
> >  {
> >  	u32 residency_C0_up = 0, residency_C0_down = 0;
> > -	u8 new_delay, adj;
> > +	int new_delay, adj;
> >  
> >  	dev_priv->rps.ei_interrupt_count++;
> >  
> > -- 
> > 1.8.3.1
> 
> -- 
> Ville Syrjälä
> Intel OTC
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch