Quoting Ville Syrjala (2020-10-21 14:14:41)
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> A bunch of the ips calculations require 64bit math. In particular
> 'corr' and 'corr2' look like they can overflow on 32bit systems.
> Switch to explicit u64 for those.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/intel_rps.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c b/drivers/gpu/drm/i915/gt/intel_rps.c
> index e0db7541dbfa..1cf48c51a93e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rps.c
> +++ b/drivers/gpu/drm/i915/gt/intel_rps.c
> @@ -1281,8 +1281,9 @@ static unsigned long __ips_gfx_val(struct intel_ips *ips)
> {
> struct intel_rps *rps = container_of(ips, typeof(*rps), ips);
> struct intel_uncore *uncore = rps_to_uncore(rps);
> - unsigned long t, corr, state1, corr2, state2;
> + unsigned int t, state1, state2;
> u32 pxvid, ext_v;
> + u64 corr, corr2;
>
> lockdep_assert_held(&mchdev_lock);
>
> @@ -1303,11 +1304,10 @@ static unsigned long __ips_gfx_val(struct intel_ips *ips)
> else /* < 50 */
> corr = t * 301 + 1004;
>
> - corr = corr * 150142 * state1 / 10000 - 78642;
> - corr /= 100000;
> - corr2 = corr * ips->corr;
> + corr = div_u64(corr * 150142 * state1, 10000) - 78642;
u64 = (u64 * int * uint) / u32 - int
> + corr2 = div_u64(corr, 100000) * ips->corr;
u64 = u64 / u32 * u8
>
> - state2 = corr2 * state1 / 10000;
> + state2 = div_u64(corr2 * state1, 10000);
uint = (u64 * uint) / u32
> state2 /= 100; /* convert to mW */
I stared at this and wondered if they could be too big. The unsigned
long is a bit of a give away.
div_u64 == u64/u32, check.
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
-Chris
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
