Re: [PATCH v2 3/4] drm/i915: fix 64bit divide

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Nov 13, 2017 at 06:44:47PM +0000, Matthew Auld wrote:
> On 13 November 2017 at 18:19, Lionel Landwerlin
> <lionel.g.landwerlin@intel.com> wrote:
> > ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!
> > ERROR: "__divdi3" [drivers/gpu/drm/i915/i915.ko] undefined!
> >
> > We can also drop an if() as we divide by (value + 1) only if value is
> > not 0.
> >
> > Fixes: dab9178333 ("drm/i915: expose command stream timestamp frequency to userspace")
> > Reported-by: Matthew Auld <matthew.auld@intel.com>
> > Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_device_info.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
> > index 78bf7374fbdd..992ae1bdfb3b 100644
> > --- a/drivers/gpu/drm/i915/intel_device_info.c
> > +++ b/drivers/gpu/drm/i915/intel_device_info.c
> > @@ -336,13 +336,12 @@ static u64 read_reference_ts_freq(struct drm_i915_private *dev_priv)
> >
> >         base_freq = ((ts_override & GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DIVIDER_MASK) >>
> >                      GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DIVIDER_SHIFT) + 1;
> > -       base_freq *= 1000000;
> > +       base_freq *= 1000000ULL;
> >
> >         frac_freq = ((ts_override &
> >                       GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DENOMINATOR_MASK) >>
> >                      GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DENOMINATOR_SHIFT);
> > -       if (frac_freq != 0)
> > -               frac_freq = 1000000 / (frac_freq + 1);
> > +       frac_freq = div_u64(1000000ULL, frac_freq + 1);
> s/div_u64/div64_u64/ ?

Rather s/u64 frac_freq/u32 frac_freq/

-- 
Ville Syrjälä
Intel OTC
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