On Thu, May 27, 2021 at 10:17:20AM -0700, John Harrison wrote:
> On 5/25/2021 23:42, Matthew Brost wrote:
> > Drop the variable guc->interrupts.enabled as this variable is just
> > leading to bugs creeping into the code.
> >
> > e.g. A full GPU reset disables the GuC interrupts but forgot to clear
> > guc->interrupts.enabled, guc->interrupts.enabled being true suppresses
> > interrupts from getting re-enabled and now we are broken.
> >
> > It is harmless to enable interrupt while already enabled so let's just
> > delete this variable to avoid bugs like this going forward.
> Is it worth leaving the enabled flag in place but only using it to trip a
> WARN to catch such cases in a less catastrophic manner? Or are there valid
> reasons for calling enable when already enabled?
>
I don't think so as mentioned above a reset disables these interrupts
and if we didn't clear this field the WARN_ON would be triggered making
CI unhappy. Yes, the bug would less catastrophic but we'd still have to
waste time and energy chasing it.
Matt
> Either way, it seems like a plausible change and CI is happy with it, so:
> Reviewed-by: John Harrison <John.C.Harrison@xxxxxxxxx>
>
> John.
>
> > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/gt/uc/intel_guc.c | 27 +++++++++-----------------
> > drivers/gpu/drm/i915/gt/uc/intel_guc.h | 1 -
> > 2 files changed, 9 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > index ab2c8fe8cdfa..18da9ed15728 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > @@ -96,12 +96,9 @@ static void gen9_enable_guc_interrupts(struct intel_guc *guc)
> > assert_rpm_wakelock_held(>->i915->runtime_pm);
> > spin_lock_irq(>->irq_lock);
> > - if (!guc->interrupts.enabled) {
> > - WARN_ON_ONCE(intel_uncore_read(gt->uncore, GEN8_GT_IIR(2)) &
> > - gt->pm_guc_events);
> > - guc->interrupts.enabled = true;
> > - gen6_gt_pm_enable_irq(gt, gt->pm_guc_events);
> > - }
> > + WARN_ON_ONCE(intel_uncore_read(gt->uncore, GEN8_GT_IIR(2)) &
> > + gt->pm_guc_events);
> > + gen6_gt_pm_enable_irq(gt, gt->pm_guc_events);
> > spin_unlock_irq(>->irq_lock);
> > }
> > @@ -112,7 +109,6 @@ static void gen9_disable_guc_interrupts(struct intel_guc *guc)
> > assert_rpm_wakelock_held(>->i915->runtime_pm);
> > spin_lock_irq(>->irq_lock);
> > - guc->interrupts.enabled = false;
> > gen6_gt_pm_disable_irq(gt, gt->pm_guc_events);
> > @@ -134,18 +130,14 @@ static void gen11_reset_guc_interrupts(struct intel_guc *guc)
> > static void gen11_enable_guc_interrupts(struct intel_guc *guc)
> > {
> > struct intel_gt *gt = guc_to_gt(guc);
> > + u32 events = REG_FIELD_PREP(ENGINE1_MASK, GUC_INTR_GUC2HOST);
> > spin_lock_irq(>->irq_lock);
> > - if (!guc->interrupts.enabled) {
> > - u32 events = REG_FIELD_PREP(ENGINE1_MASK, GUC_INTR_GUC2HOST);
> > -
> > - WARN_ON_ONCE(gen11_gt_reset_one_iir(gt, 0, GEN11_GUC));
> > - intel_uncore_write(gt->uncore,
> > - GEN11_GUC_SG_INTR_ENABLE, events);
> > - intel_uncore_write(gt->uncore,
> > - GEN11_GUC_SG_INTR_MASK, ~events);
> > - guc->interrupts.enabled = true;
> > - }
> > + WARN_ON_ONCE(gen11_gt_reset_one_iir(gt, 0, GEN11_GUC));
> > + intel_uncore_write(gt->uncore,
> > + GEN11_GUC_SG_INTR_ENABLE, events);
> > + intel_uncore_write(gt->uncore,
> > + GEN11_GUC_SG_INTR_MASK, ~events);
> > spin_unlock_irq(>->irq_lock);
> > }
> > @@ -154,7 +146,6 @@ static void gen11_disable_guc_interrupts(struct intel_guc *guc)
> > struct intel_gt *gt = guc_to_gt(guc);
> > spin_lock_irq(>->irq_lock);
> > - guc->interrupts.enabled = false;
> > intel_uncore_write(gt->uncore, GEN11_GUC_SG_INTR_MASK, ~0);
> > intel_uncore_write(gt->uncore, GEN11_GUC_SG_INTR_ENABLE, 0);
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > index c20f3839de12..4abc59f6f3cd 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > @@ -33,7 +33,6 @@ struct intel_guc {
> > unsigned int msg_enabled_mask;
> > struct {
> > - bool enabled;
> > void (*reset)(struct intel_guc *guc);
> > void (*enable)(struct intel_guc *guc);
> > void (*disable)(struct intel_guc *guc);
>
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