+++ /dev/null
-From 8a7bf555e2fa4a6f683a06e3b474cf4751181557 Mon Sep 17 00:00:00 2001
-From: Mario Kleiner <mario.kleiner.de@gmail.com>
-Date: Wed, 18 May 2016 14:02:46 +0200
-Subject: [PATCH] drm/vc4: Make pageflip completion handling more robust.
-
-Protect both the setup of the pageflip event and the
-latching of the new requested displaylist head pointer
-by the event lock, so we can't get into a situation
-where vc4_atomic_flush latches the new display list via
-HVS_WRITE, then immediately gets preempted before queueing
-the pageflip event, then the page-flip completes in hw and
-the vc4_crtc_handle_page_flip() runs and no-ops due to
-lack of a pending pageflip event, then vc4_atomic_flush
-continues and only then queues the pageflip event - after
-the page flip handling already no-oped. This would cause
-flip completion handling only at the next vblank - one
-frame too late.
-
-In vc4_crtc_handle_page_flip() check the actual DL head
-pointer in SCALER_DISPLACTX against the requested pointer
-for page flip to make sure that the flip actually really
-completed in the current vblank and doesn't get deferred
-to the next one because the DL head pointer was written
-a bit too late into SCALER_DISPLISTX, after start of
-vblank, and missed the boat. This avoids handling a
-pageflip completion too early - one frame too early.
-
-According to Eric, DL head pointer updates which were
-written into the HVS DISPLISTX reg get committed to hardware
-at the last pixel of active scanout. Our vblank interrupt
-handler, as triggered by PV_INT_VFP_START irq, gets to run
-earliest at the first pixel of HBLANK at the end of the
-last scanline of active scanout, ie. vblank irq handling
-runs at least 1 pixel duration after a potential pageflip
-completion happened in hardware.
-
-This ordering of events in the hardware, together with the
-lock protection and SCALER_DISPLACTX sampling of this patch,
-guarantees that pageflip completion handling only runs at
-exactly the vblank irq of actual pageflip completion in all
-cases.
-
-Background info from Eric about the relative timing of
-HVS, PV's and trigger points for interrupts, DL updates:
-
-https://lists.freedesktop.org/archives/dri-devel/2016-May/107510.html
-
-Tested on RPi 2B with hardware timing measurement equipment
-and shown to no longer complete flips too early or too late.
-
-Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
-Reviewed-by: Eric Anholt <eric@anholt.net>
-(cherry picked from commit 56d1fe0979dc9b73c1c12ee07722ac380d42a0c4)
----
- drivers/gpu/drm/vc4/vc4_crtc.c | 28 ++++++++++++++++++----------
- drivers/gpu/drm/vc4/vc4_regs.h | 4 ++++
- 2 files changed, 22 insertions(+), 10 deletions(-)
-
---- a/drivers/gpu/drm/vc4/vc4_crtc.c
-+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
-@@ -465,14 +465,6 @@ static void vc4_crtc_atomic_flush(struct
-
- WARN_ON_ONCE(dlist_next - dlist_start != vc4_state->mm.size);
-
-- HVS_WRITE(SCALER_DISPLISTX(vc4_crtc->channel),
-- vc4_state->mm.start);
--
-- if (debug_dump_regs) {
-- DRM_INFO("CRTC %d HVS after:\n", drm_crtc_index(crtc));
-- vc4_hvs_dump_state(dev);
-- }
--
- if (crtc->state->event) {
- unsigned long flags;
-
-@@ -482,8 +474,20 @@ static void vc4_crtc_atomic_flush(struct
-
- spin_lock_irqsave(&dev->event_lock, flags);
- vc4_crtc->event = crtc->state->event;
-- spin_unlock_irqrestore(&dev->event_lock, flags);
- crtc->state->event = NULL;
-+
-+ HVS_WRITE(SCALER_DISPLISTX(vc4_crtc->channel),
-+ vc4_state->mm.start);
-+
-+ spin_unlock_irqrestore(&dev->event_lock, flags);
-+ } else {
-+ HVS_WRITE(SCALER_DISPLISTX(vc4_crtc->channel),
-+ vc4_state->mm.start);
-+ }
-+
-+ if (debug_dump_regs) {
-+ DRM_INFO("CRTC %d HVS after:\n", drm_crtc_index(crtc));
-+ vc4_hvs_dump_state(dev);
- }
- }
-
-@@ -509,10 +513,14 @@ static void vc4_crtc_handle_page_flip(st
- {
- struct drm_crtc *crtc = &vc4_crtc->base;
- struct drm_device *dev = crtc->dev;
-+ struct vc4_dev *vc4 = to_vc4_dev(dev);
-+ struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc->state);
-+ u32 chan = vc4_crtc->channel;
- unsigned long flags;
-
- spin_lock_irqsave(&dev->event_lock, flags);
-- if (vc4_crtc->event) {
-+ if (vc4_crtc->event &&
-+ (vc4_state->mm.start == HVS_READ(SCALER_DISPLACTX(chan)))) {
- drm_crtc_send_vblank_event(crtc, vc4_crtc->event);
- vc4_crtc->event = NULL;
- drm_crtc_vblank_put(crtc);
---- a/drivers/gpu/drm/vc4/vc4_regs.h
-+++ b/drivers/gpu/drm/vc4/vc4_regs.h
-@@ -343,6 +343,10 @@
- #define SCALER_DISPLACT0 0x00000030
- #define SCALER_DISPLACT1 0x00000034
- #define SCALER_DISPLACT2 0x00000038
-+#define SCALER_DISPLACTX(x) (SCALER_DISPLACT0 + \
-+ (x) * (SCALER_DISPLACT1 - \
-+ SCALER_DISPLACT0))
-+
- #define SCALER_DISPCTRL0 0x00000040
- # define SCALER_DISPCTRLX_ENABLE BIT(31)
- # define SCALER_DISPCTRLX_RESET BIT(30)
projects / openwrt / staging / yousong.git / blobdiff