On Wed, Oct 04, 2023 at 02:04:07PM +0200, Nirmoy Das wrote: > Take the mcr lock only when driver needs to write into a mcr based > tlb based registers. > > To prevent GT reset interference, employ gt->reset.mutex instead, since > intel_gt_mcr_multicast_write relies on gt->uncore->lock not being held. This looks a lot like protecting code and not protecting data [1] But to be really honest I'm afraid we were already doing this before this patch but with 2 other locks instead. [1] - https://blog.ffwll.ch/2022/07/locking-engineering.html > > v2: remove unused var, flags. > > Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx> > --- > drivers/gpu/drm/i915/gt/intel_tlb.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.c b/drivers/gpu/drm/i915/gt/intel_tlb.c > index 139608c30d97..0ad905df4a98 100644 > --- a/drivers/gpu/drm/i915/gt/intel_tlb.c > +++ b/drivers/gpu/drm/i915/gt/intel_tlb.c > @@ -52,15 +52,13 @@ static void mmio_invalidate_full(struct intel_gt *gt) > struct intel_engine_cs *engine; > intel_engine_mask_t awake, tmp; > enum intel_engine_id id; > - unsigned long flags; > > if (GRAPHICS_VER(i915) < 8) > return; > > intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL); > > - intel_gt_mcr_lock(gt, &flags); > - spin_lock(&uncore->lock); /* serialise invalidate with GT reset */ > + mutex_lock(>->reset.mutex);/* serialise invalidate with GT reset */ I'm still looking at this and the commit message above and trying to understand why we are doing this and changing the previous 2 by this other one. why? > > awake = 0; > for_each_engine(engine, gt, id) { > @@ -68,9 +66,9 @@ static void mmio_invalidate_full(struct intel_gt *gt) > continue; > > if (engine->tlb_inv.mcr) > - intel_gt_mcr_multicast_write_fw(gt, > - engine->tlb_inv.reg.mcr_reg, > - engine->tlb_inv.request); > + intel_gt_mcr_multicast_write(gt, > + engine->tlb_inv.reg.mcr_reg, > + engine->tlb_inv.request); you are already taking the forcewake_all domain above, so you wouldn't need to convert this to the variant that grabs the forcewake underneath. Also this is not mentioned in the commit message above. > else > intel_uncore_write_fw(uncore, > engine->tlb_inv.reg.reg, > @@ -90,8 +88,7 @@ static void mmio_invalidate_full(struct intel_gt *gt) > IS_ALDERLAKE_P(i915))) > intel_uncore_write_fw(uncore, GEN12_OA_TLB_INV_CR, 1); > > - spin_unlock(&uncore->lock); > - intel_gt_mcr_unlock(gt, flags); > + mutex_unlock(>->reset.mutex); > > for_each_engine_masked(engine, gt, awake, tmp) { > if (wait_for_invalidate(engine)) > -- > 2.41.0 >
