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Diffstat (limited to 'target/linux/brcm2708/patches-4.9/0166-drm-vc4-Fix-race-between-page-flip-completion-event-.patch')
-rw-r--r--target/linux/brcm2708/patches-4.9/0166-drm-vc4-Fix-race-between-page-flip-completion-event-.patch93
1 files changed, 93 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.9/0166-drm-vc4-Fix-race-between-page-flip-completion-event-.patch b/target/linux/brcm2708/patches-4.9/0166-drm-vc4-Fix-race-between-page-flip-completion-event-.patch
new file mode 100644
index 0000000000..3c66fefafd
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.9/0166-drm-vc4-Fix-race-between-page-flip-completion-event-.patch
@@ -0,0 +1,93 @@
+From d7f32f81cf7579ac7d13127db88e789ea864824c Mon Sep 17 00:00:00 2001
+From: Derek Foreman <derekf@osg.samsung.com>
+Date: Thu, 24 Nov 2016 12:11:55 -0600
+Subject: [PATCH] drm/vc4: Fix race between page flip completion event and
+ clean-up
+
+There was a small window where a userspace program could submit
+a pageflip after receiving a pageflip completion event yet still
+receive EBUSY.
+
+Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
+Signed-off-by: Eric Anholt <eric@anholt.net>
+Reviewed-by: Eric Anholt <eric@anholt.net>
+Reviewed-by: Daniel Stone <daniels@collabora.com>
+(cherry picked from commit 26fc78f6fef39b9d7a15def5e7e9826ff68303f4)
+---
+ drivers/gpu/drm/vc4/vc4_crtc.c | 8 ++++++++
+ drivers/gpu/drm/vc4/vc4_drv.h | 1 +
+ drivers/gpu/drm/vc4/vc4_kms.c | 33 +++++++++++++++++++++++++--------
+ 3 files changed, 34 insertions(+), 8 deletions(-)
+
+--- a/drivers/gpu/drm/vc4/vc4_crtc.c
++++ b/drivers/gpu/drm/vc4/vc4_crtc.c
+@@ -682,6 +682,14 @@ void vc4_disable_vblank(struct drm_devic
+ CRTC_WRITE(PV_INTEN, 0);
+ }
+
++/* Must be called with the event lock held */
++bool vc4_event_pending(struct drm_crtc *crtc)
++{
++ struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
++
++ return !!vc4_crtc->event;
++}
++
+ static void vc4_crtc_handle_page_flip(struct vc4_crtc *vc4_crtc)
+ {
+ struct drm_crtc *crtc = &vc4_crtc->base;
+--- a/drivers/gpu/drm/vc4/vc4_drv.h
++++ b/drivers/gpu/drm/vc4/vc4_drv.h
+@@ -445,6 +445,7 @@ int vc4_bo_stats_debugfs(struct seq_file
+ extern struct platform_driver vc4_crtc_driver;
+ int vc4_enable_vblank(struct drm_device *dev, unsigned int crtc_id);
+ void vc4_disable_vblank(struct drm_device *dev, unsigned int crtc_id);
++bool vc4_event_pending(struct drm_crtc *crtc);
+ int vc4_crtc_debugfs_regs(struct seq_file *m, void *arg);
+ int vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id,
+ unsigned int flags, int *vpos, int *hpos,
+--- a/drivers/gpu/drm/vc4/vc4_kms.c
++++ b/drivers/gpu/drm/vc4/vc4_kms.c
+@@ -119,17 +119,34 @@ static int vc4_atomic_commit(struct drm_
+
+ /* Make sure that any outstanding modesets have finished. */
+ if (nonblock) {
+- ret = down_trylock(&vc4->async_modeset);
+- if (ret) {
++ struct drm_crtc *crtc;
++ struct drm_crtc_state *crtc_state;
++ unsigned long flags;
++ bool busy = false;
++
++ /*
++ * If there's an undispatched event to send then we're
++ * obviously still busy. If there isn't, then we can
++ * unconditionally wait for the semaphore because it
++ * shouldn't be contended (for long).
++ *
++ * This is to prevent a race where queuing a new flip
++ * from userspace immediately on receipt of an event
++ * beats our clean-up and returns EBUSY.
++ */
++ spin_lock_irqsave(&dev->event_lock, flags);
++ for_each_crtc_in_state(state, crtc, crtc_state, i)
++ busy |= vc4_event_pending(crtc);
++ spin_unlock_irqrestore(&dev->event_lock, flags);
++ if (busy) {
+ kfree(c);
+ return -EBUSY;
+ }
+- } else {
+- ret = down_interruptible(&vc4->async_modeset);
+- if (ret) {
+- kfree(c);
+- return ret;
+- }
++ }
++ ret = down_interruptible(&vc4->async_modeset);
++ if (ret) {
++ kfree(c);
++ return ret;
+ }
+
+ ret = drm_atomic_helper_prepare_planes(dev, state);