From 2ca9faa551c4c97610bb0209e20c7231a93712ff Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 5 Apr 2017 16:30:54 +0100
Subject: [PATCH] drm/i915: Assert the engine is idle before overwiting the HWS
Git-commit: 2ca9faa551c4c97610bb0209e20c7231a93712ff
Patch-mainline: v4.13-rc1
References: FATE#322643 bsc#1055900
When we update the global seqno (on the engine timeline), we modify HW
state (both registers and mapped pages). As we do this, we should be
sure that the HW is idle and we are not causing a conflict. The caller
is supposed to wait_for_idle before calling us to update the seqno, so
let's assert they have and the engine is indeed idle.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170405153055.28123-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/gpu/drm/i915/i915_gem_request.c | 2 +-
drivers/gpu/drm/i915/intel_engine_cs.c | 4 ++++
2 files changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -214,8 +214,8 @@ static int reset_all_global_seqno(struct
}
/* Finally reset hw state */
- tl->seqno = seqno;
intel_engine_init_global_seqno(engine, seqno);
+ tl->seqno = seqno;
list_for_each_entry(timeline, &i915->gt.timelines, link)
memset(timeline->engine[id].sync_seqno, 0,
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -223,6 +223,8 @@ void intel_engine_init_global_seqno(stru
{
struct drm_i915_private *dev_priv = engine->i915;
+ GEM_BUG_ON(!intel_engine_is_idle(engine));
+
/* Our semaphore implementation is strictly monotonic (i.e. we proceed
* so long as the semaphore value in the register/page is greater
* than the sync value), so whenever we reset the seqno,
@@ -260,6 +262,8 @@ void intel_engine_init_global_seqno(stru
* there are any waiters for that seqno.
*/
intel_engine_wakeup(engine);
+
+ GEM_BUG_ON(intel_engine_get_seqno(engine) != seqno);
}
static void intel_engine_init_timeline(struct intel_engine_cs *engine)