Hi

Am 30.06.21 um 12:49 schrieb Daniel Vetter:
On Wed, Jun 30, 2021 at 11:52:27AM +0200, Thomas Zimmermann wrote:
The code in xcs_resume() probably didn't work as intended. It uses
struct drm_device.irq, which is allocated to 0, but never initialized
by i915 to the device's interrupt number.

v3:
        * also use intel_synchronize_hardirq() at another callsite
v2:
        * wrap irq code in intel_synchronize_hardirq() (Ville)

Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
Fixes: 536f77b1caa0 ("drm/i915/gt: Call stop_ring() from ring resume, again")
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
Cc: Lucas De Marchi <lucas.demar...@intel.com>
---
  drivers/gpu/drm/i915/gt/intel_engine_cs.c       | 2 +-
  drivers/gpu/drm/i915/gt/intel_ring_submission.c | 2 +-
  drivers/gpu/drm/i915/i915_irq.c                 | 5 +++++
  drivers/gpu/drm/i915/i915_irq.h                 | 1 +
  4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c 
b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 88694822716a..5ca3d1664335 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1229,7 +1229,7 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
                return true;
/* Waiting to drain ELSP? */
-       synchronize_hardirq(to_pci_dev(engine->i915->drm.dev)->irq);
+       intel_synchronize_hardirq(engine->i915);
        intel_engine_flush_submission(engine);
/* ELSP is empty, but there are ready requests? E.g. after reset */
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c 
b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 5d42a12ef3d6..1b5a22a83db6 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -185,7 +185,7 @@ static int xcs_resume(struct intel_engine_cs *engine)
                     ring->head, ring->tail);
/* Double check the ring is empty & disabled before we resume */
-       synchronize_hardirq(engine->i915->drm.irq);
+       intel_synchronize_hardirq(engine->i915);
        if (!stop_ring(engine))
                goto err;
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 7d0ce8b9f8ed..2203dca19895 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -4575,3 +4575,8 @@ void intel_synchronize_irq(struct drm_i915_private *i915)
  {
        synchronize_irq(to_pci_dev(i915->drm.dev)->irq);
  }
+
+void intel_synchronize_hardirq(struct drm_i915_private *i915)
+{
+       synchronize_hardirq(to_pci_dev(i915->drm.dev)->irq);

I honestly think the hardirq here is about as much cargo-culted as using
the wrong irq number.

I'd just use intel_synchronize_irq in both places and see whether CI
complains, then go with that.

Well, ok. I don't think I have Sandybridge HW available. Would the Intel CI infrastructure catch any problems with such a change?

Best regards
Thomas

-Daniel

+}
diff --git a/drivers/gpu/drm/i915/i915_irq.h b/drivers/gpu/drm/i915/i915_irq.h
index db34d5dbe402..e43b6734f21b 100644
--- a/drivers/gpu/drm/i915/i915_irq.h
+++ b/drivers/gpu/drm/i915/i915_irq.h
@@ -94,6 +94,7 @@ void intel_runtime_pm_disable_interrupts(struct 
drm_i915_private *dev_priv);
  void intel_runtime_pm_enable_interrupts(struct drm_i915_private *dev_priv);
  bool intel_irqs_enabled(struct drm_i915_private *dev_priv);
  void intel_synchronize_irq(struct drm_i915_private *i915);
+void intel_synchronize_hardirq(struct drm_i915_private *i915);
int intel_get_crtc_scanline(struct intel_crtc *crtc);
  void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv,
--
2.32.0



--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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