| Message ID | 20201021131443.25616-3-ville.syrjala@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] drm/i915: Restore ILK-M RPS support | expand |
Quoting Ville Syrjala (2020-10-21 14:14:41) > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > 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@linux.intel.com> > --- > 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@chris-wilson.co.uk> -Chris
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; + corr2 = div_u64(corr, 100000) * ips->corr; - state2 = corr2 * state1 / 10000; + state2 = div_u64(corr2 * state1, 10000); state2 /= 100; /* convert to mW */ __gen5_ips_update(ips);