drm/i915: Use new CRC debugfs API

The core provides now an ABI to userspace for generation of frame CRCs,
so implement the ->set_crc_source() callback and reuse as much code as
possible with the previous ABI implementation.

When handling the pageflip interrupt, we skip 1 or 2 frames depending on
the HW because they contain wrong values. For the legacy ABI for
generating frame CRCs, this was done in userspace but now that we have a
generic ABI it's better if it's not exposed by the kernel.

v2:
    - Leave the legacy implementation in place as the ABI implementation
      in the core is incompatible with it.
v3:
    - Use the "cooked" vblank counter so we have a whole 32 bits.
    - Make sure we don't mess with the state of the legacy CRC capture
      ABI implementation.
v4:
    - Keep use of get_vblank_counter as in the legacy code, will be
      changed in a followup commit.

v5:
    - Skip first frame or two as it's known that they contain wrong
      data.
    - A few fixes suggested by Emil Velikov.

v6:
    - Rework programming of the HW registers to preserve previous
      behavior.

v7:
    - Address whitespace issue.
    - Added a comment on why in the implementation of the new ABI we
      skip the 1st or 2nd frames.

v9:
    - Add stub for intel_crtc_set_crc_source.

v12:
    - Rebased.
    - Remove stub for intel_crtc_set_crc_source and instead set the
      callback to NULL (Jani Nikula).

v15:
    - Rebased.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Robert Foss <robert.foss@collabora.com>

irq
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170110134305.26326-2-tomeu.vizoso@collabora.com

1 files changed, 52 insertions, 25 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index a0e70f5..b9beb59 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1553,41 +1553,68 @@ static void display_pipe_crc_irq_handler(struct drm_i915_private *dev_priv,
 {
 	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[pipe];
 	struct intel_pipe_crc_entry *entry;
+	struct intel_crtc *crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
+	struct drm_driver *driver = dev_priv->drm.driver;
+	uint32_t crcs[5];
 	int head, tail;
+	u32 frame;
 
 	spin_lock(&pipe_crc->lock);
+	if (pipe_crc->source) {
+		if (!pipe_crc->entries) {
+			spin_unlock(&pipe_crc->lock);
+			DRM_DEBUG_KMS("spurious interrupt\n");
+			return;
+		}
 
-	if (!pipe_crc->entries) {
-		spin_unlock(&pipe_crc->lock);
-		DRM_DEBUG_KMS("spurious interrupt\n");
-		return;
-	}
-
-	head = pipe_crc->head;
-	tail = pipe_crc->tail;
+		head = pipe_crc->head;
+		tail = pipe_crc->tail;
 
-	if (CIRC_SPACE(head, tail, INTEL_PIPE_CRC_ENTRIES_NR) < 1) {
-		spin_unlock(&pipe_crc->lock);
-		DRM_ERROR("CRC buffer overflowing\n");
-		return;
-	}
+		if (CIRC_SPACE(head, tail, INTEL_PIPE_CRC_ENTRIES_NR) < 1) {
+			spin_unlock(&pipe_crc->lock);
+			DRM_ERROR("CRC buffer overflowing\n");
+			return;
+		}
 
-	entry = &pipe_crc->entries[head];
+		entry = &pipe_crc->entries[head];
 
-	entry->frame = dev_priv->drm.driver->get_vblank_counter(&dev_priv->drm,
-								 pipe);
-	entry->crc[0] = crc0;
-	entry->crc[1] = crc1;
-	entry->crc[2] = crc2;
-	entry->crc[3] = crc3;
-	entry->crc[4] = crc4;
+		entry->frame = driver->get_vblank_counter(&dev_priv->drm, pipe);
+		entry->crc[0] = crc0;
+		entry->crc[1] = crc1;
+		entry->crc[2] = crc2;
+		entry->crc[3] = crc3;
+		entry->crc[4] = crc4;
 
-	head = (head + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1);
-	pipe_crc->head = head;
+		head = (head + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1);
+		pipe_crc->head = head;
 
-	spin_unlock(&pipe_crc->lock);
+		spin_unlock(&pipe_crc->lock);
 
-	wake_up_interruptible(&pipe_crc->wq);
+		wake_up_interruptible(&pipe_crc->wq);
+	} else {
+		/*
+		 * For some not yet identified reason, the first CRC is
+		 * bonkers. So let's just wait for the next vblank and read
+		 * out the buggy result.
+		 *
+		 * On CHV sometimes the second CRC is bonkers as well, so
+		 * don't trust that one either.
+		 */
+		if (pipe_crc->skipped == 0 ||
+		    (IS_CHERRYVIEW(dev_priv) && pipe_crc->skipped == 1)) {
+			pipe_crc->skipped++;
+			spin_unlock(&pipe_crc->lock);
+			return;
+		}
+		spin_unlock(&pipe_crc->lock);
+		crcs[0] = crc0;
+		crcs[1] = crc1;
+		crcs[2] = crc2;
+		crcs[3] = crc3;
+		crcs[4] = crc4;
+		frame = driver->get_vblank_counter(&dev_priv->drm, pipe);
+		drm_crtc_add_crc_entry(&crtc->base, true, frame, crcs);
+	}
 }
 #else
 static inline void