drm/komeda: Fix handling of atomic commits in the atomic_commit_tail hook

[ Upstream commit eaa225b6b52233d45457fd33730e1528c604d92d ]

Komeda driver relies on the generic DRM atomic helper functions to handle
commits. It only implements an atomic_commit_tail hook for the
mode_config_helper_funcs and even that one is pretty close to the generic
implementation with the exception of additional dma_fence signalling.

What the generic helper framework doesn't do is waiting for the actual
hardware to signal that the commit parameters have been written into the
appropriate registers. As we signal CRTC events only on the irq handlers,
we need to flush the configuration and wait for the hardware to respond.

Add the Komeda specific implementation for atomic_commit_hw_done() that
flushes and waits for flip done before calling drm_atomic_helper_commit_hw_done().

The fix was prompted by a patch from Carsten Haitzler where he was trying to
solve the same issue but in a different way that I think can lead to wrong
event signaling to userspace.

Reported-by: Carsten Haitzler <carsten.haitzler@arm.com>
Tested-by: Carsten Haitzler <carsten.haitzler@arm.com>
Reviewed-by: Carsten Haitzler <carsten.haitzler@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220722122139.288486-1-liviu.dudau@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
index 59172acb973803d29c853ea4f2ad9a5538770ae3..292f533d8cf0de66f10c2c4345c5a026f86cfbbe 100644 (file)
--- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
@@ -235,7 +235,7 @@ void komeda_crtc_handle_event(struct komeda_crtc   *kcrtc,
                        crtc->state->event = NULL;
                        drm_crtc_send_vblank_event(crtc, event);
                } else {
-                       DRM_WARN("CRTC[%d]: FLIP happen but no pending commit.\n",
+                       DRM_WARN("CRTC[%d]: FLIP happened but no pending commit.\n",
                                 drm_crtc_index(&kcrtc->base));
                }
                spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
@@ -286,7 +286,7 @@ komeda_crtc_atomic_enable(struct drm_crtc *crtc,
        komeda_crtc_do_flush(crtc, old);
 }
 
-static void
+void
 komeda_crtc_flush_and_wait_for_flip_done(struct komeda_crtc *kcrtc,
                                         struct completion *input_flip_done)
 {

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
index 93b7f09b96ca95041ee25760df81d2e4c1f19547..327051bba5b688e0cb16ab58801b8331d9c485be 100644 (file)
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
@@ -69,6 +69,25 @@ static const struct drm_driver komeda_kms_driver = {
        .minor = 1,
 };
 
+static void komeda_kms_atomic_commit_hw_done(struct drm_atomic_state *state)
+{
+       struct drm_device *dev = state->dev;
+       struct komeda_kms_dev *kms = to_kdev(dev);
+       int i;
+
+       for (i = 0; i < kms->n_crtcs; i++) {
+               struct komeda_crtc *kcrtc = &kms->crtcs[i];
+
+               if (kcrtc->base.state->active) {
+                       struct completion *flip_done = NULL;
+                       if (kcrtc->base.state->event)
+                               flip_done = kcrtc->base.state->event->base.completion;
+                       komeda_crtc_flush_and_wait_for_flip_done(kcrtc, flip_done);
+               }
+       }
+       drm_atomic_helper_commit_hw_done(state);
+}
+
 static void komeda_kms_commit_tail(struct drm_atomic_state *old_state)
 {
        struct drm_device *dev = old_state->dev;
@@ -81,7 +100,7 @@ static void komeda_kms_commit_tail(struct drm_atomic_state *old_state)
 
        drm_atomic_helper_commit_modeset_enables(dev, old_state);
 
-       drm_atomic_helper_commit_hw_done(old_state);
+       komeda_kms_atomic_commit_hw_done(old_state);
 
        drm_atomic_helper_wait_for_flip_done(dev, old_state);
 

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.h b/drivers/gpu/drm/arm/display/komeda/komeda_kms.h
index 456f3c4357193172a6b5e75b50432dd1833b8b70..bf6e8fba506133567504c606c4f6964178ac840d 100644 (file)
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.h
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.h
@@ -182,6 +182,8 @@ void komeda_kms_cleanup_private_objs(struct komeda_kms_dev *kms);
 
 void komeda_crtc_handle_event(struct komeda_crtc   *kcrtc,
                              struct komeda_events *evts);
+void komeda_crtc_flush_and_wait_for_flip_done(struct komeda_crtc *kcrtc,
+                                             struct completion *input_flip_done);
 
 struct komeda_kms_dev *komeda_kms_attach(struct komeda_dev *mdev);
 void komeda_kms_detach(struct komeda_kms_dev *kms);