drm/i915: kill waiting_seqno

The waiting_seqno is not terribly useful, and as such we can remove it
so that we'll be able to extract lockless code.

v2: Keep the information for error_state (Chris)
Check if ring is initialized in hangcheck (Chris)
Capture the waiting ring (Chris)

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: add some bikeshed to clarify a comment.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

5 files changed, 11 insertions, 10 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 8ed034233e38..9d4bf6bfc46a 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -414,8 +414,6 @@ static void i915_ring_seqno_info(struct seq_file *m,
         if (ring->get_seqno) {
                 seq_printf(m, "Current sequence (%s): %d\n",
                            ring->name, ring->get_seqno(ring));
-                seq_printf(m, "Waiter sequence (%s):  %d\n",
-                           ring->name, ring->waiting_seqno);
                 seq_printf(m, "IRQ sequence (%s):     %d\n",
                            ring->name, ring->irq_seqno);
         }
@@ -687,6 +685,7 @@ static void i915_ring_error_state(struct seq_file *m,
                            error->semaphore_mboxes[ring][1]);
         }
         seq_printf(m, "  seqno: 0x%08x\n", error->seqno[ring]);
+        seq_printf(m, "  waiting: %s\n", yesno(error->waiting[ring]));
         seq_printf(m, "  ring->head: 0x%08x\n", error->cpu_ring_head[ring]);
         seq_printf(m, "  ring->tail: 0x%08x\n", error->cpu_ring_tail[ring]);
 }
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e719522cb40b..ca13098c7573 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -174,6 +174,7 @@ struct drm_i915_error_state {
         u32 eir;
         u32 pgtbl_er;
         u32 ier;
+        bool waiting[I915_NUM_RINGS];
         u32 pipestat[I915_MAX_PIPES];
         u32 tail[I915_NUM_RINGS];
         u32 head[I915_NUM_RINGS];
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f194603140c0..292b4a9e7bab 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1864,7 +1864,6 @@ i915_wait_request(struct intel_ring_buffer *ring,
         if (!i915_seqno_passed(ring->get_seqno(ring), seqno)) {
                 trace_i915_gem_request_wait_begin(ring, seqno);
 
-                ring->waiting_seqno = seqno;
                 if (ring->irq_get(ring)) {
                         if (dev_priv->mm.interruptible)
                                 ret = wait_event_interruptible(ring->irq_queue,
@@ -1880,7 +1879,6 @@ i915_wait_request(struct intel_ring_buffer *ring,
                                                              seqno) ||
                                            atomic_read(&dev_priv->mm.wedged), 3000))
                         ret = -EBUSY;
-                ring->waiting_seqno = 0;
 
                 trace_i915_gem_request_wait_end(ring, seqno);
         }
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 0acadc5e02d2..a0129cfc3b31 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1031,6 +1031,7 @@ static void i915_record_ring_state(struct drm_device *dev,
                 error->instdone[ring->id] = I915_READ(INSTDONE);
         }
 
+        error->waiting[ring->id] = waitqueue_active(&ring->irq_queue);
         error->instpm[ring->id] = I915_READ(RING_INSTPM(ring->mmio_base));
         error->seqno[ring->id] = ring->get_seqno(ring);
         error->acthd[ring->id] = intel_ring_get_active_head(ring);
@@ -1708,14 +1709,17 @@ ring_last_seqno(struct intel_ring_buffer *ring)
 
 static bool i915_hangcheck_ring_idle(struct intel_ring_buffer *ring, bool *err)
 {
+        /* We don't check whether the ring even exists before calling this
+         * function. Hence check whether it's initialized. */
+        if (ring->obj == NULL)
+                return true;
+
         if (list_empty(&ring->request_list) ||
             i915_seqno_passed(ring->get_seqno(ring), ring_last_seqno(ring))) {
                 /* Issue a wake-up to catch stuck h/w. */
-                if (ring->waiting_seqno && waitqueue_active(&ring->irq_queue)) {
-                        DRM_ERROR("Hangcheck timer elapsed... %s idle [waiting on %d, at %d], missed IRQ?\n",
-                                  ring->name,
-                                  ring->waiting_seqno,
-                                  ring->get_seqno(ring));
+                if (waitqueue_active(&ring->irq_queue)) {
+                        DRM_ERROR("Hangcheck timer elapsed... %s idle\n",
+                                  ring->name);
                         wake_up_all(&ring->irq_queue);
                         *err = true;
                 }
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index e0b25bb2fb5d..d3bf2595589f 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -60,7 +60,6 @@ struct  intel_ring_buffer {
         u32             irq_enable_mask;        /* bitmask to enable ring interrupt */
         u32             irq_seqno;              /* last seq seem at irq time */
         u32             trace_irq_seqno;
-        u32             waiting_seqno;
         u32             sync_seqno[I915_NUM_RINGS-1];
         bool __must_check (*irq_get)(struct intel_ring_buffer *ring);
         void            (*irq_put)(struct intel_ring_buffer *ring);