Quoting Mika Kuoppala (2018-02-15 15:21:33)
> Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
>
> > Keep the master iir and use it to reduce the number of reads and writes
> > to the GT iir array, i.e. only the bits marked as set by the master iir
> > are valid inside GT iir array and will be handled during the interrupt.
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/i915_irq.c | 51 +++++++++++++++++++++++++----------------
> > 1 file changed, 31 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> > index b886bd459acc..b7b377ba7b6e 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -1416,6 +1416,14 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir, int test_shift)
> > static void gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
> > u32 master_ctl, u32 gt_iir[4])
> > {
> > +#define GEN8_GT_IRQS (GEN8_GT_RCS_IRQ | \
> > + GEN8_GT_BCS_IRQ | \
> > + GEN8_GT_VCS1_IRQ | \
> > + GEN8_GT_VCS2_IRQ | \
> > + GEN8_GT_VECS_IRQ | \
> > + GEN8_GT_PM_IRQ | \
> > + GEN8_GT_GUC_IRQ)
> > +
> > if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
> > gt_iir[0] = I915_READ_FW(GEN8_GT_IIR(0));
> > if (gt_iir[0])
> > @@ -1446,31 +1454,34 @@ static void gen8_gt_irq_ack(struct drm_i915_private *dev_priv,
> > }
> >
> > static void gen8_gt_irq_handler(struct drm_i915_private *dev_priv,
> > - u32 gt_iir[4])
> > + u32 master_ctl, u32 gt_iir[4])
> > {
> > - if (gt_iir[0]) {
> > + if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
> > gen8_cs_irq_handler(dev_priv->engine[RCS],
> > gt_iir[0], GEN8_RCS_IRQ_SHIFT);
> > gen8_cs_irq_handler(dev_priv->engine[BCS],
> > gt_iir[0], GEN8_BCS_IRQ_SHIFT);
> > }
> >
> > - if (gt_iir[1]) {
> > + if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
> > gen8_cs_irq_handler(dev_priv->engine[VCS],
> > gt_iir[1], GEN8_VCS1_IRQ_SHIFT);
> > gen8_cs_irq_handler(dev_priv->engine[VCS2],
> > gt_iir[1], GEN8_VCS2_IRQ_SHIFT);
> > }
> >
> > - if (gt_iir[3])
> > + if (master_ctl & GEN8_GT_VECS_IRQ) {
> > gen8_cs_irq_handler(dev_priv->engine[VECS],
> > gt_iir[3], GEN8_VECS_IRQ_SHIFT);
> > + }
> >
> > - if (gt_iir[2] & dev_priv->pm_rps_events)
> > - gen6_rps_irq_handler(dev_priv, gt_iir[2]);
> > + if (master_ctl & (GEN8_GT_PM_IRQ | GEN8_GT_GUC_IRQ)) {
> > + if (gt_iir[2] & dev_priv->pm_rps_events)
> > + gen6_rps_irq_handler(dev_priv, gt_iir[2]);
> >
> > - if (gt_iir[2] & dev_priv->pm_guc_events)
> > - gen9_guc_irq_handler(dev_priv, gt_iir[2]);
> > + if (gt_iir[2] & dev_priv->pm_guc_events)
> > + gen9_guc_irq_handler(dev_priv, gt_iir[2]);
> > + }
> > }
> >
> > static bool bxt_port_hotplug_long_detect(enum port port, u32 val)
> > @@ -2085,9 +2096,9 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
> >
> > do {
> > u32 master_ctl, iir;
> > - u32 gt_iir[4] = {};
> > u32 pipe_stats[I915_MAX_PIPES] = {};
> > u32 hotplug_status = 0;
> > + u32 gt_iir[4];
> > u32 ier = 0;
> >
> > master_ctl = I915_READ(GEN8_MASTER_IRQ) & ~GEN8_MASTER_IRQ_CONTROL;
> > @@ -2140,7 +2151,7 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
> > I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
> > POSTING_READ(GEN8_MASTER_IRQ);
> >
> > - gen8_gt_irq_handler(dev_priv, gt_iir);
> > + gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir);
> >
> > if (hotplug_status)
> > i9xx_hpd_irq_handler(dev_priv, hotplug_status);
> > @@ -2675,10 +2686,9 @@ gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
> >
> > static irqreturn_t gen8_irq_handler(int irq, void *arg)
> > {
> > - struct drm_device *dev = arg;
> > - struct drm_i915_private *dev_priv = to_i915(dev);
> > + struct drm_i915_private *dev_priv = to_i915(arg);
> > u32 master_ctl;
> > - u32 gt_iir[4] = {};
> > + u32 gt_iir[4];
> >
> > if (!intel_irqs_enabled(dev_priv))
> > return IRQ_NONE;
> > @@ -2690,18 +2700,19 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
> >
> > I915_WRITE_FW(GEN8_MASTER_IRQ, 0);
> >
> > - /* IRQs are synced during runtime_suspend, we don't require a wakeref */
> > - disable_rpm_wakeref_asserts(dev_priv);
> > -
> > /* Find, clear, then process each source of interrupt */
> > gen8_gt_irq_ack(dev_priv, master_ctl, gt_iir);
> > - gen8_gt_irq_handler(dev_priv, gt_iir);
> > - gen8_de_irq_handler(dev_priv, master_ctl);
> > +
> > + /* IRQs are synced during runtime_suspend, we don't require a wakeref */
> > + if (master_ctl & ~GEN8_GT_IRQS) {
> > + disable_rpm_wakeref_asserts(dev_priv);
> > + gen8_de_irq_handler(dev_priv, master_ctl);
> > + enable_rpm_wakeref_asserts(dev_priv);
> > + }
> >
> > I915_WRITE_FW(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
> > - POSTING_READ_FW(GEN8_MASTER_IRQ);
> >
> > - enable_rpm_wakeref_asserts(dev_priv);
> > + gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir);
>
> You want to serve display first? Do you recommend the
> same approach to gen11?
The idea is that having squirrel the iir and acked the secondary
sources, we re-enabled the primary interrupt so that we service the next
interrupt quicker; whilst we continue to process the previous irq on
this cpu. Not sure if it makes a big difference in the end, we have a
lot of serialisation to overcome, but it's a nice consequence of Ville's
cleanup of splitting the ack/processing of the sources.
-Chris
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