[Intel-gfx] [PATCH v2 3/4] drm/i915: fix 64bit divide

[Matthew Auld]

On 13 November 2017 at 18:19, Lionel Landwerlin
<lionel.g.landwerlin at 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 at intel.com>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at 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/ ?

>
>         return base_freq + frac_freq;
>  }
> @@ -360,7 +359,7 @@ static u64 read_timestamp_frequency(struct drm_i915_private *dev_priv)
>                  *      hclks." (through the “Clocking Configuration”
>                  *      (“CLKCFG”) MCHBAR register)
>                  */
> -               return (dev_priv->rawclk_freq * 1000) / 16;
> +               return div_u64(dev_priv->rawclk_freq * 1000ULL, 16);
Why do we need this?

>         } else if (INTEL_GEN(dev_priv) <= 8) {
>                 /* PRMs say:
>                  *
> --
> 2.15.0
>
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