We're seeing a GPU HANG issue on a CHV platform, which was caused by
bac24f59f454 ("drm/i915/execlists: Enable coarse preemption boundaries for 
gen8").

Gen8 platform has only timeslice and doesn't support a preemption mechanism
as engines do not have a preemption timer and doesn't send an irq if the
preemption timeout expires. So, add a fix to not consider preemption
during dequeuing for gen8 platforms.

Also move can_preemt() above need_preempt() function to resolve implicit
declaration of function ‘can_preempt' error and make can_preempt()
function param as const to resolve error: passing argument 1 of
‘can_preempt’ discards ‘const’ qualifier from the pointer target type.

Fixes: bac24f59f454 ("drm/i915/execlists: Enable coarse preemption boundaries 
for gen8")
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11396
Suggested-by: Andi Shyti <andi.sh...@intel.com>
Signed-off-by: Nitin Gote <nitin.r.g...@intel.com>
Cc: Chris Wilson <chris.p.wil...@linux.intel.com>
CC: <sta...@vger.kernel.org> # v5.2+
---
 .../drm/i915/gt/intel_execlists_submission.c  | 24 ++++++++++++-------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c 
b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 21829439e686..30631cc690f2 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -294,11 +294,26 @@ static int virtual_prio(const struct 
intel_engine_execlists *el)
        return rb ? rb_entry(rb, struct ve_node, rb)->prio : INT_MIN;
 }
 
+static bool can_preempt(const struct intel_engine_cs *engine)
+{
+       if (GRAPHICS_VER(engine->i915) > 8)
+               return true;
+
+       if (IS_CHERRYVIEW(engine->i915) || IS_BROADWELL(engine->i915))
+               return false;
+
+       /* GPGPU on bdw requires extra w/a; not implemented */
+       return engine->class != RENDER_CLASS;
+}
+
 static bool need_preempt(const struct intel_engine_cs *engine,
                         const struct i915_request *rq)
 {
        int last_prio;
 
+       if ((GRAPHICS_VER(engine->i915) <= 8) && can_preempt(engine))
+               return false;
+
        if (!intel_engine_has_semaphores(engine))
                return false;
 
@@ -3313,15 +3328,6 @@ static void remove_from_engine(struct i915_request *rq)
        i915_request_notify_execute_cb_imm(rq);
 }
 
-static bool can_preempt(struct intel_engine_cs *engine)
-{
-       if (GRAPHICS_VER(engine->i915) > 8)
-               return true;
-
-       /* GPGPU on bdw requires extra w/a; not implemented */
-       return engine->class != RENDER_CLASS;
-}
-
 static void kick_execlists(const struct i915_request *rq, int prio)
 {
        struct intel_engine_cs *engine = rq->engine;
-- 
2.25.1

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