Quoting Chris Wilson (2021-02-02 15:53:41)
> Quoting Tvrtko Ursulin (2021-02-02 15:49:59)
> >
> > On 02/02/2021 15:14, Chris Wilson wrote:
> > > The different submission backends each have their own preferred
> > > behaviour and interrupt setup. Let each handle their own interrupts.
> > >
> > > This becomes more useful later as we to extract the use of auxiliary
> > > state in the interrupt handler that is backend specific.
> > >
> > > Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> > > ---
> > > drivers/gpu/drm/i915/gt/intel_engine_cs.c | 7 ++
> > > drivers/gpu/drm/i915/gt/intel_engine_types.h | 14 +---
> > > .../drm/i915/gt/intel_execlists_submission.c | 40 +++++++++
> > > drivers/gpu/drm/i915/gt/intel_gt_irq.c | 82 ++++++-------------
> > > drivers/gpu/drm/i915/gt/intel_gt_irq.h | 7 ++
> > > .../gpu/drm/i915/gt/intel_ring_submission.c | 7 ++
> > > drivers/gpu/drm/i915/gt/intel_rps.c | 2 +-
> > > .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 10 ++-
> > > drivers/gpu/drm/i915/i915_irq.c | 8 +-
> > > 9 files changed, 103 insertions(+), 74 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > index dab8d734e272..2a453ba5f25a 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > > @@ -255,6 +255,11 @@ static void intel_engine_sanitize_mmio(struct
> > > intel_engine_cs *engine)
> > > intel_engine_set_hwsp_writemask(engine, ~0u);
> > > }
> > >
> > > +static void nop_irq_handler(struct intel_engine_cs *engine, u32 iir)
> > > +{
> > > + GEM_DEBUG_WARN_ON(iir);
> > > +}
> > > +
> > > static int intel_engine_setup(struct intel_gt *gt, enum intel_engine_id
> > > id)
> > > {
> > > const struct engine_info *info = &intel_engines[id];
> > > @@ -292,6 +297,8 @@ static int intel_engine_setup(struct intel_gt *gt,
> > > enum intel_engine_id id)
> > > engine->hw_id = info->hw_id;
> > > engine->guc_id = MAKE_GUC_ID(info->class, info->instance);
> > >
> > > + engine->irq_handler = nop_irq_handler;
> > > +
> > > engine->class = info->class;
> > > engine->instance = info->instance;
> > > __sprint_engine_name(engine);
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > index 9d59de5c559a..7fd035d45263 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
> > > @@ -402,6 +402,7 @@ struct intel_engine_cs {
> > > u32 irq_enable_mask; /* bitmask to enable ring
> > > interrupt */
> > > void (*irq_enable)(struct intel_engine_cs *engine);
> > > void (*irq_disable)(struct intel_engine_cs *engine);
> > > + void (*irq_handler)(struct intel_engine_cs *engine, u32
> > > iir);
> > >
> > > void (*sanitize)(struct intel_engine_cs *engine);
> > > int (*resume)(struct intel_engine_cs *engine);
> > > @@ -481,10 +482,9 @@ struct intel_engine_cs {
> > > #define I915_ENGINE_HAS_PREEMPTION BIT(2)
> > > #define I915_ENGINE_HAS_SEMAPHORES BIT(3)
> > > #define I915_ENGINE_HAS_TIMESLICES BIT(4)
> > > -#define I915_ENGINE_NEEDS_BREADCRUMB_TASKLET BIT(5)
> > > -#define I915_ENGINE_IS_VIRTUAL BIT(6)
> > > -#define I915_ENGINE_HAS_RELATIVE_MMIO BIT(7)
> > > -#define I915_ENGINE_REQUIRES_CMD_PARSER BIT(8)
> > > +#define I915_ENGINE_IS_VIRTUAL BIT(5)
> > > +#define I915_ENGINE_HAS_RELATIVE_MMIO BIT(6)
> > > +#define I915_ENGINE_REQUIRES_CMD_PARSER BIT(7)
> > > unsigned int flags;
> > >
> > > /*
> > > @@ -588,12 +588,6 @@ intel_engine_has_timeslices(const struct
> > > intel_engine_cs *engine)
> > > return engine->flags & I915_ENGINE_HAS_TIMESLICES;
> > > }
> > >
> > > -static inline bool
> > > -intel_engine_needs_breadcrumb_tasklet(const struct intel_engine_cs
> > > *engine)
> > > -{
> > > - return engine->flags & I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
> > > -}
> > > -
> > > static inline bool
> > > intel_engine_is_virtual(const struct intel_engine_cs *engine)
> > > {
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > index 4ddd2099a931..ed62e4b549d2 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > > @@ -2394,6 +2394,45 @@ static void execlists_submission_tasklet(struct
> > > tasklet_struct *t)
> > > rcu_read_unlock();
> > > }
> > >
> > > +static void execlists_irq_handler(struct intel_engine_cs *engine, u32
> > > iir)
> > > +{
> > > + bool tasklet = false;
> > > +
> > > + if (unlikely(iir & GT_CS_MASTER_ERROR_INTERRUPT)) {
> > > + u32 eir;
> > > +
> > > + /* Upper 16b are the enabling mask, rsvd for internal
> > > errors */
> > > + eir = ENGINE_READ(engine, RING_EIR) & GENMASK(15, 0);
> > > + ENGINE_TRACE(engine, "CS error: %x\n", eir);
> > > +
> > > + /* Disable the error interrupt until after the reset */
> > > + if (likely(eir)) {
> > > + ENGINE_WRITE(engine, RING_EMR, ~0u);
> > > + ENGINE_WRITE(engine, RING_EIR, eir);
> > > + WRITE_ONCE(engine->execlists.error_interrupt, eir);
> > > + tasklet = true;
> > > + }
> > > + }
> > > +
> > > + if (iir & GT_WAIT_SEMAPHORE_INTERRUPT) {
> > > + WRITE_ONCE(engine->execlists.yield,
> > > + ENGINE_READ_FW(engine, RING_EXECLIST_STATUS_HI));
> > > + ENGINE_TRACE(engine, "semaphore yield: %08x\n",
> > > + engine->execlists.yield);
> > > + if (del_timer(&engine->execlists.timer))
> > > + tasklet = true;
> > > + }
> > > +
> > > + if (iir & GT_CONTEXT_SWITCH_INTERRUPT)
> > > + tasklet = true;
> > > +
> > > + if (iir & GT_RENDER_USER_INTERRUPT)
> > > + intel_engine_signal_breadcrumbs(engine);
> > > +
> > > + if (tasklet)
> > > + tasklet_hi_schedule(&engine->execlists.tasklet);
> > > +}
> > > +
> > > static void __execlists_kick(struct intel_engine_execlists *execlists)
> > > {
> > > /* Kick the tasklet for some interrupt coalescing and reset
> > > handling */
> > > @@ -3146,6 +3185,7 @@ logical_ring_default_vfuncs(struct intel_engine_cs
> > > *engine)
> > > * until a more refined solution exists.
> > > */
> > > }
> > > + engine->irq_handler = execlists_irq_handler;
> > >
> > > engine->flags |= I915_ENGINE_SUPPORTS_STATS;
> > > if (!intel_vgpu_active(engine->i915)) {
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> > > b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> > > index 9fc6c912a4e5..f5aa31ae8f6c 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> > > +++ b/drivers/gpu/drm/i915/gt/intel_gt_irq.c
> > > @@ -20,48 +20,6 @@ static void guc_irq_handler(struct intel_guc *guc, u16
> > > iir)
> > > intel_guc_to_host_event_handler(guc);
> > > }
> > >
> > > -static void
> > > -cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
> > > -{
> > > - bool tasklet = false;
> > > -
> > > - if (unlikely(iir & GT_CS_MASTER_ERROR_INTERRUPT)) {
> > > - u32 eir;
> > > -
> > > - /* Upper 16b are the enabling mask, rsvd for internal
> > > errors */
> > > - eir = ENGINE_READ(engine, RING_EIR) & GENMASK(15, 0);
> > > - ENGINE_TRACE(engine, "CS error: %x\n", eir);
> > > -
> > > - /* Disable the error interrupt until after the reset */
> > > - if (likely(eir)) {
> > > - ENGINE_WRITE(engine, RING_EMR, ~0u);
> > > - ENGINE_WRITE(engine, RING_EIR, eir);
> > > - WRITE_ONCE(engine->execlists.error_interrupt, eir);
> > > - tasklet = true;
> > > - }
> > > - }
> > > -
> > > - if (iir & GT_WAIT_SEMAPHORE_INTERRUPT) {
> > > - WRITE_ONCE(engine->execlists.yield,
> > > - ENGINE_READ_FW(engine, RING_EXECLIST_STATUS_HI));
> > > - ENGINE_TRACE(engine, "semaphore yield: %08x\n",
> > > - engine->execlists.yield);
> > > - if (del_timer(&engine->execlists.timer))
> > > - tasklet = true;
> > > - }
> > > -
> > > - if (iir & GT_CONTEXT_SWITCH_INTERRUPT)
> > > - tasklet = true;
> > > -
> > > - if (iir & GT_RENDER_USER_INTERRUPT) {
> > > - intel_engine_signal_breadcrumbs(engine);
> > > - tasklet |= intel_engine_needs_breadcrumb_tasklet(engine);
> > > - }
> > > -
> > > - if (tasklet)
> > > - tasklet_hi_schedule(&engine->execlists.tasklet);
> > > -}
> > > -
> > > static u32
> > > gen11_gt_engine_identity(struct intel_gt *gt,
> > > const unsigned int bank, const unsigned int bit)
> > > @@ -122,7 +80,7 @@ gen11_engine_irq_handler(struct intel_gt *gt, const u8
> > > class,
> > > engine = NULL;
> > >
> > > if (likely(engine))
> > > - return cs_irq_handler(engine, iir);
> > > + return intel_engine_cs_irq(engine, iir);
> > >
> > > WARN_ONCE(1, "unhandled engine interrupt class=0x%x,
> > > instance=0x%x\n",
> > > class, instance);
> > > @@ -275,9 +233,12 @@ void gen11_gt_irq_postinstall(struct intel_gt *gt)
> > > void gen5_gt_irq_handler(struct intel_gt *gt, u32 gt_iir)
> > > {
> > > if (gt_iir & GT_RENDER_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(gt->engine_class[RENDER_CLASS][0]);
> > > + intel_engine_cs_irq(gt->engine_class[RENDER_CLASS][0],
> > > + gt_iir);
> > > +
> > > if (gt_iir & ILK_BSD_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(gt->engine_class[VIDEO_DECODE_CLASS][0]);
> > > + intel_engine_cs_irq(gt->engine_class[VIDEO_DECODE_CLASS][0],
> > > + gt_iir);
> > > }
> > >
> > > static void gen7_parity_error_irq_handler(struct intel_gt *gt, u32 iir)
> > > @@ -301,11 +262,16 @@ static void gen7_parity_error_irq_handler(struct
> > > intel_gt *gt, u32 iir)
> > > void gen6_gt_irq_handler(struct intel_gt *gt, u32 gt_iir)
> > > {
> > > if (gt_iir & GT_RENDER_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(gt->engine_class[RENDER_CLASS][0]);
> > > + intel_engine_cs_irq(gt->engine_class[RENDER_CLASS][0],
> > > + gt_iir);
> > > +
> > > if (gt_iir & GT_BSD_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(gt->engine_class[VIDEO_DECODE_CLASS][0]);
> > > + intel_engine_cs_irq(gt->engine_class[VIDEO_DECODE_CLASS][0],
> > > + gt_iir);
> > > +
> > > if (gt_iir & GT_BLT_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(gt->engine_class[COPY_ENGINE_CLASS][0]);
> > > + intel_engine_cs_irq(gt->engine_class[COPY_ENGINE_CLASS][0],
> > > + gt_iir);
> > >
> > > if (gt_iir & (GT_BLT_CS_ERROR_INTERRUPT |
> > > GT_BSD_CS_ERROR_INTERRUPT |
> > > @@ -324,10 +290,10 @@ void gen8_gt_irq_handler(struct intel_gt *gt, u32
> > > master_ctl)
> > > if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
> > > iir = raw_reg_read(regs, GEN8_GT_IIR(0));
> > > if (likely(iir)) {
> > > - cs_irq_handler(gt->engine_class[RENDER_CLASS][0],
> > > - iir >> GEN8_RCS_IRQ_SHIFT);
> > > -
> > > cs_irq_handler(gt->engine_class[COPY_ENGINE_CLASS][0],
> > > - iir >> GEN8_BCS_IRQ_SHIFT);
> > > +
> > > intel_engine_cs_irq(gt->engine_class[RENDER_CLASS][0],
> > > + iir >> GEN8_RCS_IRQ_SHIFT);
> > > +
> > > intel_engine_cs_irq(gt->engine_class[COPY_ENGINE_CLASS][0],
> > > + iir >> GEN8_BCS_IRQ_SHIFT);
> > > raw_reg_write(regs, GEN8_GT_IIR(0), iir);
> > > }
> > > }
> > > @@ -335,10 +301,10 @@ void gen8_gt_irq_handler(struct intel_gt *gt, u32
> > > master_ctl)
> > > if (master_ctl & (GEN8_GT_VCS0_IRQ | GEN8_GT_VCS1_IRQ)) {
> > > iir = raw_reg_read(regs, GEN8_GT_IIR(1));
> > > if (likely(iir)) {
> > > -
> > > cs_irq_handler(gt->engine_class[VIDEO_DECODE_CLASS][0],
> > > - iir >> GEN8_VCS0_IRQ_SHIFT);
> > > -
> > > cs_irq_handler(gt->engine_class[VIDEO_DECODE_CLASS][1],
> > > - iir >> GEN8_VCS1_IRQ_SHIFT);
> > > +
> > > intel_engine_cs_irq(gt->engine_class[VIDEO_DECODE_CLASS][0],
> > > + iir >> GEN8_VCS0_IRQ_SHIFT);
> > > +
> > > intel_engine_cs_irq(gt->engine_class[VIDEO_DECODE_CLASS][1],
> > > + iir >> GEN8_VCS1_IRQ_SHIFT);
> > > raw_reg_write(regs, GEN8_GT_IIR(1), iir);
> > > }
> > > }
> > > @@ -346,8 +312,8 @@ void gen8_gt_irq_handler(struct intel_gt *gt, u32
> > > master_ctl)
> > > if (master_ctl & GEN8_GT_VECS_IRQ) {
> > > iir = raw_reg_read(regs, GEN8_GT_IIR(3));
> > > if (likely(iir)) {
> > > -
> > > cs_irq_handler(gt->engine_class[VIDEO_ENHANCEMENT_CLASS][0],
> > > - iir >> GEN8_VECS_IRQ_SHIFT);
> > > +
> > > intel_engine_cs_irq(gt->engine_class[VIDEO_ENHANCEMENT_CLASS][0],
> > > + iir >> GEN8_VECS_IRQ_SHIFT);
> > > raw_reg_write(regs, GEN8_GT_IIR(3), iir);
> > > }
> > > }
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_irq.h
> > > b/drivers/gpu/drm/i915/gt/intel_gt_irq.h
> > > index f667e976fb2b..601473fe9df9 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_gt_irq.h
> > > +++ b/drivers/gpu/drm/i915/gt/intel_gt_irq.h
> > > @@ -8,6 +8,8 @@
> > >
> > > #include <linux/types.h>
> > >
> > > +#include "intel_engine_types.h"
> > > +
> > > struct intel_gt;
> > >
> > > #define GEN8_GT_IRQS (GEN8_GT_RCS_IRQ | \
> > > @@ -39,4 +41,9 @@ void gen8_gt_irq_handler(struct intel_gt *gt, u32
> > > master_ctl);
> > > void gen8_gt_irq_reset(struct intel_gt *gt);
> > > void gen8_gt_irq_postinstall(struct intel_gt *gt);
> > >
> > > +static inline void intel_engine_cs_irq(struct intel_engine_cs *engine,
> > > u32 iir)
> > > +{
> > > + engine->irq_handler(engine, iir);
> > > +}
> > > +
> > > #endif /* INTEL_GT_IRQ_H */
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > index 3cb2ce503544..9b5bfbe79347 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > +++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
> > > @@ -997,10 +997,17 @@ static void ring_release(struct intel_engine_cs
> > > *engine)
> > > intel_timeline_put(engine->legacy.timeline);
> > > }
> > >
> > > +static void irq_handler(struct intel_engine_cs *engine, u32 iir)
> > > +{
> > > + intel_engine_signal_breadcrumbs(engine);
> > > +}
> > > +
> > > static void setup_irq(struct intel_engine_cs *engine)
> > > {
> > > struct drm_i915_private *i915 = engine->i915;
> > >
> > > + engine->irq_handler = irq_handler;
> > > +
> > > if (INTEL_GEN(i915) >= 6) {
> > > engine->irq_enable = gen6_irq_enable;
> > > engine->irq_disable = gen6_irq_disable;
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c
> > > b/drivers/gpu/drm/i915/gt/intel_rps.c
> > > index 405d814e9040..4ba6a33f65cf 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_rps.c
> > > +++ b/drivers/gpu/drm/i915/gt/intel_rps.c
> > > @@ -1774,7 +1774,7 @@ void gen6_rps_irq_handler(struct intel_rps *rps,
> > > u32 pm_iir)
> > > return;
> > >
> > > if (pm_iir & PM_VEBOX_USER_INTERRUPT)
> > > - intel_engine_signal_breadcrumbs(gt->engine[VECS0]);
> > > + intel_engine_cs_irq(gt->engine[VECS0], pm_iir);
> > >
> > > if (pm_iir & PM_VEBOX_CS_ERROR_INTERRUPT)
> > > DRM_DEBUG("Command parser error, pm_iir 0x%08x\n", pm_iir);
> > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > index 17b551a0c89f..96a38466299e 100644
> > > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > > @@ -264,6 +264,14 @@ static void guc_submission_tasklet(struct
> > > tasklet_struct *t)
> > > spin_unlock_irqrestore(&engine->active.lock, flags);
> > > }
> > >
> > > +static void cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
> > > +{
> > > + if (iir & GT_RENDER_USER_INTERRUPT) {
> > > + intel_engine_signal_breadcrumbs(engine);
> > > + tasklet_hi_schedule(&engine->execlists.tasklet);
> > > + }
> > > +}
> > > +
> > > static void guc_reset_prepare(struct intel_engine_cs *engine)
> > > {
> > > struct intel_engine_execlists * const execlists =
> > > &engine->execlists;
> > > @@ -645,7 +653,6 @@ static void guc_default_vfuncs(struct intel_engine_cs
> > > *engine)
> > > }
> > > engine->set_default_submission = guc_set_default_submission;
> > >
> > > - engine->flags |= I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
> > > engine->flags |= I915_ENGINE_HAS_PREEMPTION;
> > >
> > > /*
> > > @@ -681,6 +688,7 @@ static void rcs_submission_override(struct
> > > intel_engine_cs *engine)
> > > static inline void guc_default_irqs(struct intel_engine_cs *engine)
> > > {
> > > engine->irq_keep_mask = GT_RENDER_USER_INTERRUPT;
> > > + engine->irq_handler = cs_irq_handler;
> > > }
> > >
> > > int intel_guc_submission_setup(struct intel_engine_cs *engine)
> > > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > > b/drivers/gpu/drm/i915/i915_irq.c
> > > index 9d47da8ec86d..37a48402adc1 100644
> > > --- a/drivers/gpu/drm/i915/i915_irq.c
> > > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > > @@ -3954,7 +3954,7 @@ static irqreturn_t i8xx_irq_handler(int irq, void
> > > *arg)
> > > intel_uncore_write16(&dev_priv->uncore, GEN2_IIR, iir);
> > >
> > > if (iir & I915_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(dev_priv->gt.engine[RCS0]);
> > > + intel_engine_cs_irq(dev_priv->gt.engine[RCS0], iir);
> > >
> > > if (iir & I915_MASTER_ERROR_INTERRUPT)
> > > i8xx_error_irq_handler(dev_priv, eir, eir_stuck);
> > > @@ -4062,7 +4062,7 @@ static irqreturn_t i915_irq_handler(int irq, void
> > > *arg)
> > > intel_uncore_write(&dev_priv->uncore, GEN2_IIR, iir);
> > >
> > > if (iir & I915_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(dev_priv->gt.engine[RCS0]);
> > > + intel_engine_cs_irq(dev_priv->gt.engine[RCS0], iir);
> > >
> > > if (iir & I915_MASTER_ERROR_INTERRUPT)
> > > i9xx_error_irq_handler(dev_priv, eir, eir_stuck);
> > > @@ -4207,10 +4207,10 @@ static irqreturn_t i965_irq_handler(int irq, void
> > > *arg)
> > > intel_uncore_write(&dev_priv->uncore, GEN2_IIR, iir);
> > >
> > > if (iir & I915_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(dev_priv->gt.engine[RCS0]);
> > > + intel_engine_cs_irq(dev_priv->gt.engine[RCS0], iir);
> > >
> > > if (iir & I915_BSD_USER_INTERRUPT)
> > > -
> > > intel_engine_signal_breadcrumbs(dev_priv->gt.engine[VCS0]);
> > > + intel_engine_cs_irq(dev_priv->gt.engine[VCS0], iir);
> > >
> > > if (iir & I915_MASTER_ERROR_INTERRUPT)
> > > i9xx_error_irq_handler(dev_priv, eir, eir_stuck);
> > >
> >
> > Looks believable as design cleanup.
> >
> > Wonder if some barrier is neded after overwriting the nop handler to be
> > sure it propagates to all CPUs by the time interrupts get enabled. Maybe
> > we have enough sync points between the two events. Or add a paranoid
> > setter with some barrier - what would be required to flush the write to
> > all cores? smp_store_mb?
>
> Hmm. Indeed, that seems justified. So justified I expect it's already
> taken care of for us on installing the irq handler. Let's have a look.
Ok. There are plenty of mutex/spin/mmio to install an interrupt.
i915_driver_mmio_probe -> intel_gt_init_mmio -> intel_engine_init_mmio ->
nop_irq_handler
intel_irq_install
i915_gem_init -> intel_gt_init -> intel_engines_init -> assign real
engine->irq_handler
So all that is irrelevant. We change the engine->irq_handler while the
interrupts are live. And we may get an interrupt as soon as we unmask
the engines. So err on smp_store_mb(engine->irq_handler,
real_irq_handler) does not seem to be wholly paranoid.
-Chris
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