From 582a6f90aa0d9103ab834b3a48a5bb7e4d07cac6 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 12 Sep 2019 10:29:32 +0100
Subject: drm/i915/execlists: Add a paranoid flush of the CSB pointers upon
reset
Git-commit: 582a6f90aa0d9103ab834b3a48a5bb7e4d07cac6
Patch-mainline: v5.5-rc1
References: bsc#1152489
After a GPU reset, we need to drain all the CS events so that we have an
accurate picture of the execlists state at the time of the reset. Be
paranoid and force a read of the CSB write pointer from memory.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190912092933.4729-1-chris@chris-wilson.co.uk
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index dcdf7cf66e7e..dbc90da2341a 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2359,6 +2359,10 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
struct i915_request *rq;
u32 *regs;
+ mb(); /* paranoia: read the CSB pointers from after the reset */
+ clflush(execlists->csb_write);
+ mb();
+
process_csb(engine); /* drain preemption events */
/* Following the reset, we need to reload the CSB read/write pointers */
--
2.28.0