drm/i915/gt: Call stop_ring() from ring resume, again

For reasons I cannot explain, except to say this is Sandybridge after
all, call stop_ring() again dring ring resume in order to prevent
mysterious hard hangs.

Testcase: igt/i915_selftest/hangcheck # snb
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121154950.19898-3-chris@chris-wilson.co.uk
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 4984ff5..e4db431 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -183,15 +183,36 @@ static void set_pp_dir(struct intel_engine_cs *engine)
        }
 }
 
+static bool stop_ring(struct intel_engine_cs *engine)
+{
+       /* Empty the ring by skipping to the end */
+       ENGINE_WRITE_FW(engine, RING_HEAD, ENGINE_READ_FW(engine, RING_TAIL));
+       ENGINE_POSTING_READ(engine, RING_HEAD);
+
+       /* The ring must be empty before it is disabled */
+       ENGINE_WRITE_FW(engine, RING_CTL, 0);
+       ENGINE_POSTING_READ(engine, RING_CTL);
+
+       /* Then reset the disabled ring */
+       ENGINE_WRITE_FW(engine, RING_HEAD, 0);
+       ENGINE_WRITE_FW(engine, RING_TAIL, 0);
+
+       return (ENGINE_READ_FW(engine, RING_HEAD) & HEAD_ADDR) == 0;
+}
+
 static int xcs_resume(struct intel_engine_cs *engine)
 {
-       struct drm_i915_private *dev_priv = engine->i915;
        struct intel_ring *ring = engine->legacy.ring;
 
        ENGINE_TRACE(engine, "ring:{HEAD:%04x, TAIL:%04x}\n",
                     ring->head, ring->tail);
 
-       if (HWS_NEEDS_PHYSICAL(dev_priv))
+       /* Double check the ring is empty & disabled before we resume */
+       synchronize_hardirq(engine->i915->drm.irq);
+       if (!stop_ring(engine))
+               goto err;
+
+       if (HWS_NEEDS_PHYSICAL(engine->i915))
                ring_setup_phys_status_page(engine);
        else
                ring_setup_status_page(engine);
@@ -228,21 +249,10 @@ static int xcs_resume(struct intel_engine_cs *engine)
        if (__intel_wait_for_register_fw(engine->uncore,
                                         RING_CTL(engine->mmio_base),
                                         RING_VALID, RING_VALID,
-                                        5000, 0, NULL)) {
-               drm_err(&dev_priv->drm,
-                       "%s initialization failed; "
-                       "ctl %08x (valid? %d) head %08x [%08x] tail %08x [%08x] start %08x [expected %08x]\n",
-                       engine->name,
-                       ENGINE_READ(engine, RING_CTL),
-                       ENGINE_READ(engine, RING_CTL) & RING_VALID,
-                       ENGINE_READ(engine, RING_HEAD), ring->head,
-                       ENGINE_READ(engine, RING_TAIL), ring->tail,
-                       ENGINE_READ(engine, RING_START),
-                       i915_ggtt_offset(ring->vma));
-               return -EIO;
-       }
+                                        5000, 0, NULL))
+               goto err;
 
-       if (INTEL_GEN(dev_priv) > 2)
+       if (INTEL_GEN(engine->i915) > 2)
                ENGINE_WRITE_FW(engine,
                                RING_MI_MODE, _MASKED_BIT_DISABLE(STOP_RING));
 
@@ -255,6 +265,19 @@ static int xcs_resume(struct intel_engine_cs *engine)
        /* Papering over lost _interrupts_ immediately following the restart */
        intel_engine_signal_breadcrumbs(engine);
        return 0;
+
+err:
+       drm_err(&engine->i915->drm,
+               "%s initialization failed; "
+               "ctl %08x (valid? %d) head %08x [%08x] tail %08x [%08x] start %08x [expected %08x]\n",
+               engine->name,
+               ENGINE_READ(engine, RING_CTL),
+               ENGINE_READ(engine, RING_CTL) & RING_VALID,
+               ENGINE_READ(engine, RING_HEAD), ring->head,
+               ENGINE_READ(engine, RING_TAIL), ring->tail,
+               ENGINE_READ(engine, RING_START),
+               i915_ggtt_offset(ring->vma));
+       return -EIO;
 }
 
 static void sanitize_hwsp(struct intel_engine_cs *engine)
@@ -290,23 +313,6 @@ static void xcs_sanitize(struct intel_engine_cs *engine)
        clflush_cache_range(engine->status_page.addr, PAGE_SIZE);
 }
 
-static bool stop_ring(struct intel_engine_cs *engine)
-{
-       /* Empty the ring by skipping to the end */
-       ENGINE_WRITE_FW(engine, RING_HEAD, ENGINE_READ_FW(engine, RING_TAIL));
-       ENGINE_POSTING_READ(engine, RING_HEAD);
-
-       /* The ring must be empty before it is disabled */
-       ENGINE_WRITE_FW(engine, RING_CTL, 0);
-       ENGINE_POSTING_READ(engine, RING_CTL);
-
-       /* Then reset the disabled ring */
-       ENGINE_WRITE_FW(engine, RING_HEAD, 0);
-       ENGINE_WRITE_FW(engine, RING_TAIL, 0);
-
-       return (ENGINE_READ_FW(engine, RING_HEAD) & HEAD_ADDR) == 0;
-}
-
 static void reset_prepare(struct intel_engine_cs *engine)
 {
        /*
@@ -329,25 +335,23 @@ static void reset_prepare(struct intel_engine_cs *engine)
 
        if (!stop_ring(engine)) {
                /* G45 ring initialization often fails to reset head to zero */
-               drm_dbg(&engine->i915->drm,
-                       "%s head not reset to zero "
-                       "ctl %08x head %08x tail %08x start %08x\n",
-                       engine->name,
-                       ENGINE_READ_FW(engine, RING_CTL),
-                       ENGINE_READ_FW(engine, RING_HEAD),
-                       ENGINE_READ_FW(engine, RING_TAIL),
-                       ENGINE_READ_FW(engine, RING_START));
-       }
-
-       if (!stop_ring(engine)) {
-               drm_err(&engine->i915->drm,
-                       "failed to set %s head to zero "
-                       "ctl %08x head %08x tail %08x start %08x\n",
-                       engine->name,
-                       ENGINE_READ_FW(engine, RING_CTL),
-                       ENGINE_READ_FW(engine, RING_HEAD),
-                       ENGINE_READ_FW(engine, RING_TAIL),
-                       ENGINE_READ_FW(engine, RING_START));
+               ENGINE_TRACE(engine,
+                            "HEAD not reset to zero, "
+                            "{ CTL:%08x, HEAD:%08x, TAIL:%08x, START:%08x }\n",
+                            ENGINE_READ_FW(engine, RING_CTL),
+                            ENGINE_READ_FW(engine, RING_HEAD),
+                            ENGINE_READ_FW(engine, RING_TAIL),
+                            ENGINE_READ_FW(engine, RING_START));
+               if (!stop_ring(engine)) {
+                       drm_err(&engine->i915->drm,
+                               "failed to set %s head to zero "
+                               "ctl %08x head %08x tail %08x start %08x\n",
+                               engine->name,
+                               ENGINE_READ_FW(engine, RING_CTL),
+                               ENGINE_READ_FW(engine, RING_HEAD),
+                               ENGINE_READ_FW(engine, RING_TAIL),
+                               ENGINE_READ_FW(engine, RING_START));
+               }
        }
 }