drm/i915: semaphore debugfs

Simple debugfs file to display the current state of semaphores. This is
useful if you want to see the state without hanging the GPU.

NOTE: This patch is optional to the series.

NOTE2: Like the GPU error state collection, the reads are currently
incoherent.

v2 (Rodrigo): * Iterate only on active rings.
   	      * s/ring_buffer/engine_cs.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index bfd0d41..c1b88a8 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2395,6 +2395,76 @@ static int i915_display_info(struct seq_file *m, void *unused)
        return 0;
 }
 
+static int i915_semaphore_status(struct seq_file *m, void *unused)
+{
+       struct drm_info_node *node = (struct drm_info_node *) m->private;
+       struct drm_device *dev = node->minor->dev;
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       struct intel_engine_cs *ring;
+       int num_rings = hweight32(INTEL_INFO(dev)->ring_mask);
+       int i, j, ret;
+
+       if (!i915_semaphore_is_enabled(dev)) {
+               seq_puts(m, "Semaphores are disabled\n");
+               return 0;
+       }
+
+       ret = mutex_lock_interruptible(&dev->struct_mutex);
+       if (ret)
+               return ret;
+
+       if (IS_BROADWELL(dev)) {
+               struct page *page;
+               uint64_t *seqno;
+
+               page = i915_gem_object_get_page(dev_priv->semaphore_obj, 0);
+
+               seqno = (uint64_t *)kmap_atomic(page);
+               for_each_ring(ring, dev_priv, i) {
+                       uint64_t offset;
+
+                       seq_printf(m, "%s\n", ring->name);
+
+                       seq_puts(m, "  Last signal:");
+                       for (j = 0; j < num_rings; j++) {
+                               offset = i * I915_NUM_RINGS + j;
+                               seq_printf(m, "0x%08llx (0x%02llx) ",
+                                          seqno[offset], offset * 8);
+                       }
+                       seq_putc(m, '\n');
+
+                       seq_puts(m, "  Last wait:  ");
+                       for (j = 0; j < num_rings; j++) {
+                               offset = i + (j * I915_NUM_RINGS);
+                               seq_printf(m, "0x%08llx (0x%02llx) ",
+                                          seqno[offset], offset * 8);
+                       }
+                       seq_putc(m, '\n');
+
+               }
+               kunmap_atomic(seqno);
+       } else {
+               seq_puts(m, "  Last signal:");
+               for_each_ring(ring, dev_priv, i)
+                       for (j = 0; j < num_rings; j++)
+                               seq_printf(m, "0x%08x\n",
+                                          I915_READ(ring->semaphore.mbox.signal[j]));
+               seq_putc(m, '\n');
+       }
+
+       seq_puts(m, "\nSync seqno:\n");
+       for_each_ring(ring, dev_priv, i) {
+               for (j = 0; j < num_rings; j++) {
+                       seq_printf(m, "  0x%08x ", ring->semaphore.sync_seqno[j]);
+               }
+               seq_putc(m, '\n');
+       }
+       seq_putc(m, '\n');
+
+       mutex_unlock(&dev->struct_mutex);
+       return 0;
+}
+
 struct pipe_crc_info {
        const char *name;
        struct drm_device *dev;
@@ -3904,6 +3974,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
        {"i915_pc8_status", i915_pc8_status, 0},
        {"i915_power_domain_info", i915_power_domain_info, 0},
        {"i915_display_info", i915_display_info, 0},
+       {"i915_semaphore_status", i915_semaphore_status, 0},
 };
 #define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)