drm/nouveau: Fix pre-nv50 pageflip events (v4)

Apparently pre-nv50 pageflip events happen before the actual vblank
period. Therefore that functionality got semi-disabled in

commit af4870e406126b7ac0ae7c7ce5751f25ebe60f28
Author: Mario Kleiner <mario.kleiner.de@gmail.com>
Date:   Tue May 13 00:42:08 2014 +0200

    drm/nouveau/kms/nv04-nv40: fix pageflip events via special case.

Unfortunately that hack got uprooted in

commit cc1ef118fc099295ae6aabbacc8af94d8d8885eb
Author: Thierry Reding <treding@nvidia.com>
Date:   Wed Aug 12 17:00:31 2015 +0200

    drm/irq: Make pipe unsigned and name consistent

Triggering a warning when trying to sample the vblank timestamp for a
non-existing pipe. There's a few ways to fix this:

- Open-code the old behaviour, which just enshrines this slight
  breakage of the userspace ABI.

- Revert Mario's commit and again inflict broken timestamps, again not
  pretty.

- Fix this for real by delaying the pageflip TS until the next vblank
  interrupt, thereby making it accurate.

This patch implements the third option. Since having a page flip
interrupt that happens when the pageflip gets armed and not when it
completes in the next vblank seems to be fairly common (older i915 hw
works very similarly) create a new helper to arm vblank events for
such drivers.

v2 (Mario Kleiner):
- Fix function prototypes in drmP.h
- Add missing vblank_put() for pageflip completion without
  pageflip event.
- Initialize sequence number for queued pageflip event to avoid
  trouble in drm_handle_vblank_events().
- Remove dead code and spelling fix.

v3 (Mario Kleiner):
- Add a signed-off-by and cc stable tag per Ilja's advice.

v4 (Thierry Reding):
- Fix kerneldoc typo, discovered by Michel Dänzer
- Rearrange tags and changelog

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=106431
Cc: Thierry Reding <treding@nvidia.com>
Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
Acked-by: Ben Skeggs <bskeggs@redhat.com>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: stable@vger.kernel.org # v4.3
Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 2151ea551d3bd6526d850754b79ece388a9279df..607f493ae80132890ad97422f58f9cdf95eefc75 100644 (file)
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -980,7 +980,8 @@ static void send_vblank_event(struct drm_device *dev,
                struct drm_pending_vblank_event *e,
                unsigned long seq, struct timeval *now)
 {
-       WARN_ON_SMP(!spin_is_locked(&dev->event_lock));
+       assert_spin_locked(&dev->event_lock);
+
        e->event.sequence = seq;
        e->event.tv_sec = now->tv_sec;
        e->event.tv_usec = now->tv_usec;
@@ -992,6 +993,57 @@ static void send_vblank_event(struct drm_device *dev,
                                         e->event.sequence);
 }
 
+/**
+ * drm_arm_vblank_event - arm vblank event after pageflip
+ * @dev: DRM device
+ * @pipe: CRTC index
+ * @e: the event to prepare to send
+ *
+ * A lot of drivers need to generate vblank events for the very next vblank
+ * interrupt. For example when the page flip interrupt happens when the page
+ * flip gets armed, but not when it actually executes within the next vblank
+ * period. This helper function implements exactly the required vblank arming
+ * behaviour.
+ *
+ * Caller must hold event lock. Caller must also hold a vblank reference for
+ * the event @e, which will be dropped when the next vblank arrives.
+ *
+ * This is the legacy version of drm_crtc_arm_vblank_event().
+ */
+void drm_arm_vblank_event(struct drm_device *dev, unsigned int pipe,
+                         struct drm_pending_vblank_event *e)
+{
+       assert_spin_locked(&dev->event_lock);
+
+       e->pipe = pipe;
+       e->event.sequence = drm_vblank_count(dev, pipe);
+       list_add_tail(&e->base.link, &dev->vblank_event_list);
+}
+EXPORT_SYMBOL(drm_arm_vblank_event);
+
+/**
+ * drm_crtc_arm_vblank_event - arm vblank event after pageflip
+ * @crtc: the source CRTC of the vblank event
+ * @e: the event to send
+ *
+ * A lot of drivers need to generate vblank events for the very next vblank
+ * interrupt. For example when the page flip interrupt happens when the page
+ * flip gets armed, but not when it actually executes within the next vblank
+ * period. This helper function implements exactly the required vblank arming
+ * behaviour.
+ *
+ * Caller must hold event lock. Caller must also hold a vblank reference for
+ * the event @e, which will be dropped when the next vblank arrives.
+ *
+ * This is the native KMS version of drm_arm_vblank_event().
+ */
+void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
+                              struct drm_pending_vblank_event *e)
+{
+       drm_arm_vblank_event(crtc->dev, drm_crtc_index(crtc), e);
+}
+EXPORT_SYMBOL(drm_crtc_arm_vblank_event);
+
 /**
  * drm_send_vblank_event - helper to send vblank event after pageflip
  * @dev: DRM device

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index db6bc676054519b08f3dbe6e45a23782362c9376..64c8d932d5f19de27aa6f66c4e5371f5484cdd7c 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -829,7 +829,6 @@ nouveau_finish_page_flip(struct nouveau_channel *chan,
        struct drm_device *dev = drm->dev;
        struct nouveau_page_flip_state *s;
        unsigned long flags;
-       int crtcid = -1;
 
        spin_lock_irqsave(&dev->event_lock, flags);
 
@@ -841,15 +840,19 @@ nouveau_finish_page_flip(struct nouveau_channel *chan,
 
        s = list_first_entry(&fctx->flip, struct nouveau_page_flip_state, head);
        if (s->event) {
-               /* Vblank timestamps/counts are only correct on >= NV-50 */
-               if (drm->device.info.family >= NV_DEVICE_INFO_V0_TESLA)
-                       crtcid = s->crtc;
+               if (drm->device.info.family < NV_DEVICE_INFO_V0_TESLA) {
+                       drm_arm_vblank_event(dev, s->crtc, s->event);
+               } else {
+                       drm_send_vblank_event(dev, s->crtc, s->event);
 
-               drm_send_vblank_event(dev, crtcid, s->event);
+                       /* Give up ownership of vblank for page-flipped crtc */
+                       drm_vblank_put(dev, s->crtc);
+               }
+       }
+       else {
+               /* Give up ownership of vblank for page-flipped crtc */
+               drm_vblank_put(dev, s->crtc);
        }
-
-       /* Give up ownership of vblank for page-flipped crtc */
-       drm_vblank_put(dev, s->crtc);
 
        list_del(&s->head);
        if (ps)

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 441b26e846d825c2d341c9fc76df2ac0f4f31f56..0a271ca1f7c7ec12199b4c9781bb5aa5ded75dae 100644 (file)
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -953,6 +953,10 @@ extern void drm_send_vblank_event(struct drm_device *dev, unsigned int pipe,
                                  struct drm_pending_vblank_event *e);
 extern void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
                                       struct drm_pending_vblank_event *e);
+extern void drm_arm_vblank_event(struct drm_device *dev, unsigned int pipe,
+                                struct drm_pending_vblank_event *e);
+extern void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
+                                     struct drm_pending_vblank_event *e);
 extern bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe);
 extern bool drm_crtc_handle_vblank(struct drm_crtc *crtc);
 extern int drm_vblank_get(struct drm_device *dev, unsigned int pipe);